This page describes how to get MyRocks in MariaDB when compiling MariaDB from source. (See Build-Steps for instructions how to build the upstream.)

Build Process and Requirements

MariaDB compile process will compile MyRocks into ha_rocksdb.so by default if the platform supports it (That is, no WITH_ROCKSDB switch is necessary).

Platform requirements:

• A 64-bit platform (due to some 32 bit compilers having difficulties with RocksDB)

• git installed (or git submodules fetched somehow)

• A sufficiently recent compiler:

  • gcc >= 4.8, or

  • clang >= 3.3, or

  • MS Visual Studio 2015 or newer

Building on Ubuntu 16.04

The steps were checked on a fresh install of Ubuntu 16.04.2 LTS Xenial.

This should produce storage/rocksdb/ha_rocksdb.so which is MyRocks storage engine in the loadable form.

Starting MyRocks

MyRocks does not require any special way to initialize the data directory. Minimal my.cnf flle:

Run the server like this

Compression libraries. Supported compression libraries are listed in . Compiling like the above, I get:

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MyRocks supports the CHECK TABLE command.

The command will do a number of checks to verify that the table data is self-consistent.

The details about the errors are printed into the error log. If log_warnings > 2, the error log will also have some informational messages which can help with troubleshooting.

Besides this, RocksDB has its own (low-level) log in #rocksdb/LOG file.

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MyRocks exposes its performance metrics through several interfaces:

• Status variables

• SHOW ENGINE ROCKSDB STATUS

• RocksDB's perf context

the contents slightly overlap, but each source has its own unique information, so be sure to check all three.

Status Variables

Check the output of

See for more information.

SHOW ENGINE ROCKSDB STATUS

This produces a lot of information.

One particularly interesting part is compaction statistics. It shows the amount of data on each SST level and other details:

Performance Context

RocksDB has an internal mechanism called "perf context". The counter values are exposed through two tables:

• - global counters

• - Per-table/partition counters

By default statistics are NOT collected. One needs to set to some value (e.g. 3) to enable collection.

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Being a write-optimized storage engine, MyRocks has special ways to load data much faster than normal INSERTs would.

See:

• the section about "Migrating from InnoDB to MyRocks in production" has some clues.

• Data-Loading covers the topic in greater detail.

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• MyRocks uses snapshot isolation.

• Support do READ-COMMITTED and REPEATABLE-READ .

• SERIALIZABLE is not supported.

FB/MySQL has added new syntax:

START TRANSACTION WITH CONSISTENT ROCKSDB|INNODB SNAPSHOT;

The statement returns the binlog coordinates pointing at the snapshot.

MariaDB (and Percona Server) support extension to the regular

START TRANSACTION WITH CONSISTENT SNAPSHOT;

syntax as documented in Enhancements for START TRANSACTION WITH CONSISTENT SNAPSHOT.

After issuing the statement, one can examine the binlog_snapshot_file and binlog_snapshot_position status variables to see the binlog position that corresponds to the snapshot.

See Also

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MyRocks is available in

• Facebook's (FB) MySQL branch (originally based on MySQL 5.6)

• MariaDB (from 10.2 and 10.3)

• Percona Server from 5.7

This page lists differences between these variants.

This is a work in progress. The contents are not final

MyRocks supports group commit with the ().

Counter Values to Watch

(The following is only necessary if you are studying MyRocks internals)

MariaDB's group commit counters are:

- how many transactions were written to the binary log

- how many group commits happened. (e.g. if each group had two transactions, this is twice as small as )

Bloom filters are used to reduce read amplification. Bloom filters can be set on a per-column family basis (see ).

Bloom Filter Parameters

• How many bits to use

MyRocks supports several compression algorithms.

Supported Compression Algorithms

Supported compression algorithms can be checked like so:

Another way to make the check is to look into #rocksdb/LOG file in the data directory. It should have lines like:

Compression Settings

Compression is set on a per-Column Family basis. See .

Checking Compression Settings

To check current compression settings for a column family one can use a query like so:

The output are like:

Current column family settings are used for the new SST files.

Modifying Compression Settings

Compression settings are not dynamic parameters, one cannot change them by setting .

The procedure to change compression settings is as follows:

• Edit my.cnf to set .

Example:

• Restart the server.

The data will not be re-compressed immediately. However, all new SST files will use the new compression settings, so as data gets inserted/updated the column family will gradually start using the new option.

Caveat: Syntax Errors

Please note that rocksdb-override-cf-options syntax is quite strict. Any typos will result in the parse error, and MyRocks plugin will not be loaded. Depending on your configuration, the server may still start. If it does start, you can use this command to check if the plugin is loaded:

(note that you need the "ROCKSDB" plugin. Other auxiliary plugins like "ROCKSDB_TRX" might still get loaded).

Another way is to detect the error is check the error log. When option parsing fails, it will contain messages like so:

Checking How the Data is Compressed

A query to check what compression is used in the SST files that store the data for a given table (test.t1):

Example output:

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This article describes how MyRocks storage engine provides statistics to the query optimizer.

There are three kinds of statistics:

• Table statistics (number of rows in the table, average row size)

• Index cardinality (how distinct values are in the index)

• records-in-range estimates (how many rows are in a certain range "const1 < tbl.key < const2".

How MyRocks computes statistics

MyRocks (actually RocksDB) uses LSM files which are written once and never updated. When an LSM file is written, MyRocks will compute index cardinalities and number-of-rows for the data in the file. (The file generally has rows, index records and/or tombstones for multiple tables/indexes).

For performance reasons, statistics are computed based on a fraction of rows in the LSM file. The percentage of rows used is controlled by ; the default value is 10%.

Before the data is dumped into LSM file, it is stored in the MemTable. MemTable doesn't allow computing index cardinalities, but it can provide an approximate number of rows in the table. Use of MemTable data for statistics is controlled by ; the default value is ON.

Are index statistics predictable?

Those who create/run MTR tests, need to know whether EXPLAIN output is deterministic. For MyRocks tables, the answer is NO (just like for InnoDB).

Statistics are computed using sampling and GetApproximateMemTableStats() which means that the #rows column in the EXPLAIN output may vary slightly.

Records-in-range estimates

MyRocks uses RocksDB's GetApproximateSizes() call to produce an estimate for the number of rows in the certain range. The data in MemTable is also taken into account by issuing a GetApproximateMemTableStats call.

ANALYZE TABLE

ANALYZE TABLE will possibly flush the MemTable (depending on the and settings).

After that, it will re-read statistics from the SST files and re-compute the summary numbers (TODO: and if the data was already on disk, the result should not be different from the one we had before ANALYZE?)

Debugging helper variables

There are a few variables that will cause MyRocks to report certain pre-defined estimate numbers to the optimizer:

• @@rocksdb_records_in_range - if not 0, report that any range has this many rows

• @@rocksdb_force_index_records_in_range - if not 0, and FORCE INDEX hint is used, report that any range has this many rows.

• @@rocksdb_debug_optimizer_n_rows - if not 0, report that any MyRocks table has this many rows.

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This article is about and index-only scans on secondary indexes. It applies to MariaDB's MyRocks, Facebook's MyRocks, and other variants.

Secondary Keys Only

The primary key in MyRocks is always the clustered key, that is, the index record is THE table record and so it's not possible to do "index only" because there isn't anything that is not in the primary key's (Key,Value) pair.

Secondary keys may or may not support index-only scans, depending on the datatypes of the columns that the query is trying to read.

MyRocks stores data in column families. These are similar to tablespaces. By default, the data is stored in the default column family.

One can specify which column family the data goes to by using index comments:

If the column name starts with rev:, the column family is reverse-ordered.

Reasons for Column Families

Storage parameters like

• Bloom filter settings

• Compression settings

• Whether the data is stored in reverse order

are specified on a per-column family basis.

Creating a Column Family

When creating a table or index, you can specify the name of the column family for it. If the column family doesn't exist, it are automatically created.

Dropping a Column Family

There is currently no way to drop a column family. RocksDB supports this internally but MyRocks doesn't provide any way to do it.

Setting Column Family Parameters

Use these variables:

• - a my.cnf parameter specifying default options for all column families.

• - a my.cnf parameter specifying per-column family option overrides.

• - a dynamically-settable variable which allows to change parameters online. Not all parameters can be changed.

rocksdb_override_cf_options

This parameter allows one to override column family options for specific column families. Here is an example of how to set option1=value1 and option2=value for column family cf1, and option3=value3 for column family cf3:

One can check the contents of INFORMATION_SCHEMA.ROCKSDB_CF_OPTIONS to see what options are available.

Options that are frequently configured are:

• Data compression. See .

• Bloom Filters. See .

Examining Column Family Parameters

See the table.

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Details about how MyRocks works with .

MyRocks and Statement-Based Replication

replication (SBR) works as follows: SQL statements are executed on the master (possibly concurrently). They are written into the binlog (this fixes their ordering, "a serialization"). The slave then reads the binlog and executes the statements in their binlog order.

In order to prevent data drift, serial execution of statements on the slave must have the same effect as concurrent execution of these statements on the master. In other words, transaction isolation on the master must be close to SERIALIZABLE transaction isolation level (This is not a strict mathematical proof but shows the idea).

This page documents status variables related to the MyRocks storage engine. See Server Status Variables for a complete list of status variables that can be viewed with SHOW STATUS.

See also the Full list of MariaDB options, system and status variables.

Rocksdb_block_cache_add

• Description: Number of blocks added to the Block Cache.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_block_cache_add_failures

• Description: Number of failures when adding blocks to Block Cache.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_block_cache_bytes_read

• Description: Bytes read from Block Cache.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_block_cache_bytes_write

• Description: Bytes written to Block Cache.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_block_cache_data_add

• Description: Number of data blocks added to the Block Cache.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_block_cache_data_bytes_insert

• Description: Bytes added to the Block Cache.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_block_cache_data_hit

• Description: Number of hits when accessing the data block from the Block Cache.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_block_cache_data_miss

• Description: Number of misses when accessing the data block from the Block Cache.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_block_cache_filter_add

• Description: Number of bloom filter blocks added to the Block Cache.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_block_cache_filter_bytes_evict

• Description: Bytes of bloom filter blocks evicted from the Block Cache.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_block_cache_filter_bytes_insert

• Description: Bytes of bloom filter blocks added to the Block Cache.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_block_cache_filter_hit

• Description: Number of hits when accessing the filter block from the Block Cache.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_block_cache_filter_miss

• Description: Number of misses when accessing the filter block from the Block Cache.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_block_cache_hit

• Description: Total number of hits for the Block Cache.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_block_cache_index_add

• Description: Number of index blocks added to Block Cache index.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_block_cache_index_bytes_evict

• Description: Bytes of index blocks evicted from the Block Cache.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_block_cache_index_bytes_insert

• Description: Bytes of index blocks added to the Block Cache.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_block_cache_index_hit

• Description: Number of hits for the Block Cache index.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_block_cache_index_miss

• Description: Number of misses for the Block Cache index.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_block_cache_miss

• Description: Total number of misses for the Block Cache.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_block_cachecompressed_hit

• Description: Number of hits for the compressed Block Cache.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_block_cachecompressed_miss

• Description: Number of misses for the compressed Block Cache.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_bloom_filter_full_positive

• Description:

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_bloom_filter_full_true_positive

• Description:

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_bloom_filter_prefix_checked

• Description: Number of times the Bloom Filter checked before creating an iterator on a file.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_bloom_filter_prefix_useful

• Description: Number of times the Bloom Filter check used to avoid creating an iterator on a file.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_bloom_filter_useful

• Description: Number of times the Bloom Filter used instead of reading form file.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_bytes_read

• Description: Total number of uncompressed bytes read from memtables, cache or table files.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_bytes_written

• Description: Total number of uncompressed bytes written.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_compact_read_bytes

• Description: Number of bytes read during compaction.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_compact_write_bytes

• Description: Number of bytes written during compaction.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_compaction_key_drop_new

• Description: Number of keys dropped during compaction due their being overwritten by new values.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_compaction_key_drop_obsolete

• Description: Number of keys dropped during compaction due to their being obsolete.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_compaction_key_drop_user

• Description: Number of keys dropped during compaction due to user compaction.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_covered_secondary_key_lookups

• Description: Incremented when avoiding reading a record via a keyread. This indicates lookups that were performed via a secondary index containing a field that is only a prefix of the column, and that could return all requested fields directly from the secondary index.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_flush_write_bytes

• Description: Number of bytes written during flush.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_get_hit_l0

• Description: Number of times reads got data from the L0 compaction layer.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_get_hit_l1

• Description: Number of times reads got data from the L1 compaction layer.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_get_hit_l2_and_up

• Description: Number of times reads got data from the L2 and up compaction layer.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_getupdatessince_calls

• Description: Number of calls to the GetUpdatesSince function. You may find this useful when monitoring refreshes of the transaction log.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_iter_bytes_read

• Description: Total uncompressed bytes read from an iterator, including the size of both key and value.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_l0_num_files_stall_micros

• Description: Shows how long in microseconds throttled due to too mnay files in L0.

• Scope: Global, Session

• Data Type: numeric

• Removed: ,

Rocksdb_l0_slowdown_micros

• Description: Total time spent waiting in microseconds while performing L0-L1 compactions.

• Scope: Global, Session

• Data Type: numeric

• Removed: ,

Rocksdb_manual_compactions_processed

• Description:

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_manual_compactions_running

• Description:

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_memtable_compaction_micros

• Description:

• Scope: Global, Session

• Data Type: numeric

• Removed: ,

Rocksdb_memtable_hit

• Description: Number of memtable hits.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_memtable_miss

• Description: Number of memtable misses.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_memtable_total

• Description: Memory used, in bytes, of all memtables.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_memtable_unflushed

• Description: Memory used, in bytes, of all unflushed memtables.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_no_file_closes

• Description: Number of times files were closed.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_no_file_errors

• Description: Number of errors encountered while trying to read data from an SST file.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_no_file_opens

• Description: Number of times files were opened.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_num_iterators

• Description: Number of iterators currently open.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_block_not_compressed

• Description: Number of uncompressed blocks.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_db_next

• Description: Number of next calls.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_number_db_next_found

• Description: Number of next calls that returned data.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_number_db_prev

• Description: Number of prev calls.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_number_db_prev_found

• Description: Number of prev calls that returned data.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_number_db_seek

• Description: Number of seek calls.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_number_db_seek_found

• Description: Number of seek calls that returned data.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_number_deletes_filtered

• Description: Number of deleted records were not written to storage due to a nonexistent key.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_keys_read

• Description: Number of keys have been read.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_keys_updated

• Description: Number of keys have been updated.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_keys_written

• Description: Number of keys have been written.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_merge_failures

• Description: Number of failures encountered while performing merge operator actions.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_multiget_bytes_read

• Description: Number of bytes read during RocksDB MultiGet() calls.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_multiget_get

• Description: Number of RocksDB MultiGet() requests made.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_multiget_keys_read

• Description: Number of keys read through RocksDB MultiGet() calls.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_reseeks_iteration

• Description: Number of reseeks that have occurred inside an iteration that skipped over a large number of keys with the same user key.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_sst_entry_delete

• Description: Number of delete markers written.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_sst_entry_merge

• Description: Number of merge keys written.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_sst_entry_other

• Description: Number of keys written that are not delete, merge or put keys.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_sst_entry_put

• Description: Number of put keys written.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_sst_entry_singledelete

• Description: Number of single-delete keys written.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_superversion_acquires

• Description: Number of times the superversion structure acquired. This is useful when tracking files for the database.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_superversion_cleanups

• Description: Number of times the superversion structure performed cleanups.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_number_superversion_releases

• Description: Number of times the superversion structure released.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_queries_point

• Description: Number of single-row queries.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_queries_range

• Description: Number of multi-row queries.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_row_lock_deadlocks

• Description: Number of deadlocks.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_row_lock_wait_timeouts

• Description: Number of row lock wait timeouts.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_rows_deleted

• Description: Number of rows deleted.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_rows_deleted_blind

• Description:

• Scope: Global, Session

• Data Type: numeric

Rocksdb_rows_expired

• Description: Number of expired rows.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_rows_filtered

• Description: Number of TTL filtered rows.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_rows_inserted

• Description: Number of rows inserted.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_rows_read

• Description: Number of rows read.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_rows_updated

• Description: Number of rows updated.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_snapshot_conflict_errors

• Description: Number of snapshot conflict errors that have occurred during transactions that forced a rollback.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_stall_l0_file_count_limit_slowdowns

• Description: Write slowdowns due to L0 being near to full.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_stall_l0_file_count_limit_stops

• Description: Write stops due to L0 being to full.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_stall_locked_l0_file_count_limit_slowdowns

• Description: Write slowdowns due to L0 being near to full and L0 compaction in progress.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_stall_locked_l0_file_count_limit_stops

• Description: Write stops due to L0 being full and L0 compaction in progress.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_stall_memtable_limit_slowdowns

• Description: Write slowdowns due to approaching maximum permitted number of memtables.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_stall_memtable_limit_stops

• Description: * Description: Write stops due to reaching maximum permitted number of memtables.

• Scope: Global, Session

• Data Type: numeric

• Introduced: ,

Rocksdb_stall_micros

• Description: Time in microseconds that the writer had to wait for the compaction or flush to complete.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_stall_pending_compaction_limit_slowdowns

• Description: Write slowdowns due to nearing the limit for the maximum number of pending compaction bytes.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_stall_pending_compaction_limit_stops

• Description: Write stops due to reaching the limit for the maximum number of pending compaction bytes.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_stall_total_slowdowns

• Description: Total number of write slowdowns.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_stall_total_stops

• Description: Total number of write stops.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_system_rows_deleted

• Description: Number of rows deleted from system tables.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_system_rows_inserted

• Description: Number of rows inserted into system tables.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_system_rows_read

• Description: Number of rows read from system tables.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_system_rows_updated

• Description: Number of rows updated for system tables.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_wal_bytes

• Description: Number of bytes written to WAL.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_wal_group_syncs

• Description: Number of group commit WAL file syncs have occurred. This is provided by MyRocks and is not a view of a RocksDB counter. Increased in rocksdb_flush_wal() when doing the rdb->FlushWAL() call.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_wal_synced

• Description: Number of syncs made on RocksDB WAL file.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_write_other

• Description: Number of writes processed by a thread other than the requesting thread.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_write_self

• Description: Number of writes processed by requesting thread.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_write_timedout

• Description: Number of writes that timed out.

• Scope: Global, Session

• Data Type: numeric

Rocksdb_write_wal

• Description: Number of write calls that requested WAL.

• Scope: Global, Session

• Data Type: numeric

_{This page is licensed: CC BY-SA / Gnu FDL}

About MyRocks for MariaDB

MyRocks is an open source storage engine that was originally developed by Facebook.

MyRocks has been extended by the MariaDB engineering team to be a pluggable storage engine that you use in your MariaDB solutions. It works seamlessly with MariaDB features. This openness in the storage layer allows you to use the right storage engine to optimize your usage requirements, which provides optimum performance. Community contributions are one of MariaDB’s greatest advantages over other databases. Under the lead of our developer Sergey Petrunia, MyRocks in MariaDB is occasionally being merged with upstream MyRocks from Facebook. See more at: facebook-myrocks-mariadb#sthash.ZlEr7kNq.dpuf

MyRocks, typically, gives greater performance for web scale type applications. It can be an ideal storage engine solution when you have workloads that require greater compression and IO efficiency. It uses a Log Structured Merge (LSM) architecture, which has advantages over B-Tree algorithms, to provide efficient data ingestion, like read-free replication slaves, or fast bulk data loading. MyRocks distinguishing features include:

• compaction filter

• merge operator

• backup

• column families

For more MyRocks features see:

Benefits

On production workloads, MyRocks was tested to prove that it provides:

Greater Space Efficiency

• 2x more compression MyRocks has 2x better compression compared to compressed InnoDB, 3-4x better compression compared to uncompressed InnoDB, meaning you use less space.

Greater Writing Efficiency

• 2x lower write rates to storage MyRocks has a 10x less write amplification compared to InnoDB, giving you better endurance of flash storage and improving overall throughput.

Faster Data Loading

• faster database loads MyRocks writes data directly onto the bottommost level, which avoids all compaction overheads when you enable faster data loading for a session.

Faster Replication

• No random reads for updating secondary keys, except for unique indexes. The Read-Free Replication option does away with random reads when updating primary keys, regardless of uniqueness, with a row-based binary logging format.

Requirements and Limitations

• MyRocks is included from .

• MyRocks is available in the MariaDB Server packages for Linux and Windows.

• Maria DB optimistic parallel replication may not be supported.

• MyRocks is not available for 32-bit platforms

MyRocks builds are available on platforms that support a sufficiently modern compiler, for example:

• Ubuntu Trusty, Xenial, (amd64 and ppc64el)

• Ubuntu Yakkety (amd64)

• Debian Jessie, stable (amd64, ppc64el)

• Debian Stretch, Sid (testing and unstable) (amd64)

_{This page is licensed: CC BY-SA / Gnu FDL}

MyRocks is a storage engine that adds the RocksDB database to MariaDB. RocksDB is an LSM database with a great compression ratio that is optimized for flash storage.

The storage engine must be installed before it can be used.

Installing the Plugin's Package

The MyRocks storage engine's shared library is included in MariaDB packages as the ha_rocksdb.so or ha_rocksdb.dll shared library on systems where it can be built.

This page documents system variables related to the MyRocks storage engine. See Server System Variables for a complete list of system variables and instructions on setting them.

See also the Full list of MariaDB options, system and status variables.

rocksdb_access_hint_on_compaction_start

• Description: DBOptions::access_hint_on_compaction_start for RocksDB. Specifies the file access pattern, applied to all input files, once a compaction starts.

• Command line: --rocksdb-access-hint-on-compaction-start=#

• Scope: Global

• Dynamic: No

• Data Type: numeric

• Default Value: 1

• Range: 0 to 3

rocksdb_advise_random_on_open

• Description: DBOptions::advise_random_on_open for RocksDB.

• Command line: --rocksdb-advise-random-on-open={0|1}

• Scope: Global

• Dynamic: No

rocksdb_allow_concurrent_memtable_write

• Description: DBOptions::allow_concurrent_memtable_write for RocksDB.

• Command line: --rocksdb-allow-concurrent-memtable-write={0|1}

• Scope: Global

• Dynamic: No

rocksdb_allow_mmap_reads

• Description: DBOptions::allow_mmap_reads for RocksDB

• Command line: --rocksdb-allow-mmap-reads={0|1}

• Scope: Global

• Dynamic: No

rocksdb_allow_mmap_writes

• Description: DBOptions::allow_mmap_writes for RocksDB

• Command line: --rocksdb-allow-mmap-writes={0|1}

• Scope: Global

• Dynamic: No

rocksdb_allow_to_start_after_corruption

• Description: Allow server still to start successfully even if RocksDB corruption is detected.

• Command line: --rocksdb-allow-to-start-after-corruption={0|1}

• Scope: Global

• Dynamic: No

rocksdb_background_sync

• Description: Turns on background syncs for RocksDB

• Command line: --rocksdb-background-sync={0|1}

• Scope: Global

• Dynamic: No

rocksdb_base_background_compactions

• Description: DBOptions::base_background_compactions for RocksDB

• Command line: --rocksdb-base-background-compactions=#

• Scope: Global

• Dynamic: No

rocksdb_blind_delete_primary_key

• Description: Deleting rows by primary key lookup, without reading rows (Blind Deletes). Blind delete is disabled if the table has secondary key.

• Command line: --rocksdb-blind-delete-primary-key={0|1}

• Scope: Global, Session

• Dynamic: Yes

rocksdb_block_cache_size

• Description: Block_cache size for RocksDB (block size 1024)

• Command line: --rocksdb-block-cache-size=#

• Scope: Global

• Dynamic: Yes

To see the statistics of block cache usage, check SHOW ENGINE ROCKSDB STATUS output (search for lines starting with rocksdb.block.cache).

One can check the size of data of the block cache in DB_BLOCK_CACHE_USAGE column of the INFORMATION_SCHEMA.ROCKSDB_DBSTATS table.

rocksdb_block_restart_interval

• Description: BlockBasedTableOptions::block_restart_interval for RocksDB

• Command line: --rocksdb-block-restart-interval=#

• Scope: Global

• Dynamic: No

rocksdb_block_size

• Description: BlockBasedTableOptions::block_size for RocksDB

• Command line: --rocksdb-block-size=#

• Scope: Global

• Dynamic: No

rocksdb_block_size_deviation

• Description: BlockBasedTableOptions::block_size_deviation for RocksDB

• Command line: --rocksdb-block-size-deviation=#

• Scope: Global

• Dynamic: No

rocksdb_bulk_load

• Description: Use bulk-load mode for inserts. This disables unique_checks and enables rocksdb_commit_in_the_middle.

• Command line: --rocksdb-bulk-load={0|1}

• Scope: Global, Session

• Dynamic: Yes

rocksdb_bulk_load_allow_sk

• Description: Allow bulk loading of sk keys during bulk-load. Can be changed only when bulk load is disabled.

• Command line: --rocksdb-bulk-load_allow_sk={0|1}

• Scope: Global, Session

• Dynamic: Yes

rocksdb_bulk_load_allow_unsorted

• Description: Allow unsorted input during bulk-load. Can be changed only when bulk load is disabled.

• Command line: --rocksdb-bulk-load_allow_unsorted={0|1}

• Scope: Global, Session

• Dynamic: Yes

rocksdb_bulk_load_size

• Description: Maximum number of records in a batch for bulk-load mode.

• Command line: --rocksdb-bulk-load-size=#

• Scope: Global, Session

• Dynamic: Yes

rocksdb_bytes_per_sync

• Description: DBOptions::bytes_per_sync for RocksDB.

• Command line: --rocksdb-bytes-per-sync=#

• Scope: Global

• Dynamic: Yes

rocksdb_cache_dump

• Description: Include RocksDB block cache content in core dump.

• Command line: --rocksdb-cache-dump={0|1}

• Scope: Global

• Dynamic: Yes

rocksdb_cache_high_pri_pool_ratio

• Description: Specify the size of block cache high-pri pool.

• Command line: --rocksdb-cache-high-pri-pool-ratio=#

• Scope: Global

• Dynamic: Yes

rocksdb_cache_index_and_filter_blocks

• Description: BlockBasedTableOptions::cache_index_and_filter_blocks for RocksDB.

• Command line: --rocksdb-cache-index-and-filter-blocks={0|1}

• Scope: Global

• Dynamic: No

rocksdb_cache_index_and_filter_with_high_priority

• Description: cache_index_and_filter_blocks_with_high_priority for RocksDB.

• Command line: --rocksdb-cache-index-and-filter-with-high-priority={0|1}

• Scope: Global

• Dynamic: No

rocksdb_checksums_pct

• Description: Percentage of rows to be checksummed.

• Command line: --rocksdb-checksums-pct=#

• Scope: Global, Session

• Dynamic: Yes

rocksdb_collect_sst_properties

• Description: Enables collecting SST file properties on each flush.

• Command line: --rocksdb-collect-sst-properties={0|1}

• Scope: Global

• Dynamic: No

rocksdb_commit_in_the_middle

• Description: Commit rows implicitly every rocksdb_bulk_load_size, on bulk load/insert, update and delete.

• Command line: --rocksdb-commit-in-the-middle={0|1}

• Scope: Global, Session

• Dynamic: Yes

rocksdb_commit_time_batch_for_recovery

• Description: TransactionOptions::commit_time_batch_for_recovery for RocksDB.

• Command line: --rocksdb-commit-time-batch-for-recovery={0|1}

• Scope: Global, Session

• Dynamic: Yes

rocksdb_compact_cf

• Description: Compact column family.

• Command line: --rocksdb-compact-cf=value

• Scope: Global

• Dynamic: Yes

rocksdb_compaction_readahead_size

• Description: DBOptions::compaction_readahead_size for RocksDB.

• Command line: --rocksdb-compaction-readahead-size=#

• Scope: Global

• Dynamic: Yes

rocksdb_compaction_sequential_deletes

• Description: RocksDB will trigger compaction for the file if it has more than this number sequential deletes per window.

• Command line: --rocksdb-compaction-sequential-deletes=#

• Scope: Global

• Dynamic: Yes

rocksdb_compaction_sequential_deletes_count_sd

• Description: Counting SingleDelete as rocksdb_compaction_sequential_deletes.

• Command line: --rocksdb-compaction-sequential-deletes-count-sd={0|1}

• Scope: Global

• Dynamic: Yes

rocksdb_compaction_sequential_deletes_file_size

• Description: Minimum file size required for compaction_sequential_deletes.

• Command line: --rocksdb-compaction-sequential-deletes-file-size=#

• Scope: Global

• Dynamic: Yes

rocksdb_compaction_sequential_deletes_window

• Description: Size of the window for counting rocksdb_compaction_sequential_deletes.

• Command line: --rocksdb-compaction-sequential-deletes-window=#

• Scope: Global

• Dynamic: Yes

rocksdb_concurrent_prepare

• Description: DBOptions::concurrent_prepare for RocksDB.

• Command line: --rocksdb-coconcurrent-prepare={0|1}

• Scope: Global

• Dynamic: No

rocksdb_create_checkpoint

• Description: Checkpoint directory.

• Command line: --rocksdb-create-checkpoint=value

• Scope: Global

• Dynamic: Yes

rocksdb_create_if_missing

• Description: DBOptions::create_if_missing for RocksDB.

• Command line: --rocksdb-create-if-missing={0|1}

• Scope: Global

• Dynamic: No

rocksdb_create_missing_column_families

• Description: DBOptions::create_missing_column_families for RocksDB.

• Command line: --rocksdb-create-missing-column-families={0|1}

• Scope: Global

• Dynamic: No

rocksdb_datadir

• Description: RocksDB data directory.

• Command line: --rocksdb-datadir[=value]

• Scope: Global

• Dynamic: No

rocksdb_db_write_buffer_size

• Description: DBOptions::db_write_buffer_size for RocksDB.

• Command line: --rocksdb-db-write-buffer-size=#

• Scope: Global

• Dynamic: No

rocksdb_deadlock_detect

• Description: Enables deadlock detection.

• Command line: --rocksdb-deadlock-detect={0|1}

• Scope: Global, Session

• Dynamic: Yes

rocksdb_deadlock_detect_depth

• Description: Number of transactions deadlock detection will traverse through before assuming deadlock.

• Command line: --rocksdb-deadlock-detect-depth=#

• Scope: Global, Session

• Dynamic: Yes

rocksdb_debug_manual_compaction_delay

• Description: For debugging purposes only. Sleeping specified seconds for simulating long running compactions.

• Command line: --rocksdb-debug_manual_compaction_delay=#

• Scope: Global

• Dynamic: Yes

rocksdb_debug_optimizer_no_zero_cardinality

• Description: If cardinality is zero, override it with some value.

• Command line: --rocksdb-debug-optimizer-no-zero-cardinality={0|1}

• Scope: Global

• Dynamic: Yes

rocksdb_debug_ttl_ignore_pk

• Description: For debugging purposes only. If true, compaction filtering will not occur on PK TTL data. This variable is a no-op in non-debug builds.

• Command line: --rocksdb-debug-ttl-ignore-pk={0|1}

• Scope: Global

• Dynamic: Yes

rocksdb_debug_ttl_read_filter_ts

• Description: For debugging purposes only. Overrides the TTL read filtering time to time + debug_ttl_read_filter_ts. A value of 0 denotes that the variable is not set. This variable is a no-op in non-debug builds.

• Command line: --rocksdb-debug-ttl-read-filter-ts=#

• Scope: Global

• Dynamic: Yes

rocksdb_debug_ttl_rec_ts

• Description: For debugging purposes only. Overrides the TTL of records to now() + debug_ttl_rec_ts. The value can be +/- to simulate a record inserted in the past vs a record inserted in the 'future'. A value of 0 denotes that the variable is not set. This variable is a no-op in non-debug builds.

• Command line: --rocksdb-debug-ttl-read-filter-ts=#

• Scope: Global

• Dynamic: Yes

rocksdb_debug_ttl_snapshot_ts

• Description: For debugging purposes only. Sets the snapshot during compaction to now() + debug_set_ttl_snapshot_ts. The value can be positive or negative to simulate a snapshot in the past vs a snapshot created in the 'future'. A value of 0 denotes that the variable is not set. This variable is a no-op in non-debug builds.

• Command line: --rocksdb-debug-ttl-snapshot-ts=#

• Scope: Global

• Dynamic: Yes

rocksdb_default_cf_options

• Description: Default cf options for RocksDB.

• Command line: --rocksdb-default-cf-options=value

• Scope: Global

• Dynamic: No

rocksdb_delayed_write_rate

• Description: DBOptions::delayed_write_rate.

• Command line: --rocksdb-delayed-write-rate=#

• Scope: Global

• Dynamic: Yes

rocksdb_delete_cf

• Description: Delete column family.

• Command line: --rocksdb-delete-cf=val

• Scope: Global

• Dynamic: No

rocksdb_delete_obsolete_files_period_micros

• Description: DBOptions::delete_obsolete_files_period_micros for RocksDB.

• Command line: --rocksdb-delete-obsolete-files-period-micros=#

• Scope: Global

• Dynamic: No

rocksdb_enable_2pc

• Description: Enable two phase commit for MyRocks. When set, MyRocks will keep its data consistent with the (in other words, the server are a crash-safe master). The consistency is achieved by doing two-phase XA commit with the binary log.

• Command line: --rocksdb-enable-2pc={0|1}

• Scope: Global

• Dynamic: Yes

rocksdb_enable_bulk_load_api

• Description: Enables using SstFileWriter for bulk loading.

• Command line: --rocksdb-enable-bulk-load-api={0|1}

• Scope: Global

• Dynamic: No

rocksdb_enable_insert_with_update_caching

• Description: Whether to enable optimization where we cache the read from a failed insertion attempt in .

• Command line: --rocksdb-enable-insert-with-update-caching={0|1}

• Scope: Global

• Dynamic: Yes

rocksdb_enable_thread_tracking

• Description: DBOptions::enable_thread_tracking for RocksDB.

• Command line: --rocksdb-enable-thread-tracking={0|1}

• Scope: Global

• Dynamic: No

rocksdb_enable_ttl

• Description: Enable expired TTL records to be dropped during compaction.

• Command line: --rocksdb-enable-ttl={0|1}

• Scope: Global

• Dynamic: Yes

rocksdb_enable_ttl_read_filtering

• Description: For tables with TTL, expired records are skipped/filtered out during processing and in query results. Disabling this will allow these records to be seen, but as a result rows may disappear in the middle of transactions as they are dropped during compaction. Use with caution.

• Command line: --rocksdb-enable-ttl-read-filtering={0|1}

• Scope: Global

• Dynamic: Yes

rocksdb_enable_write_thread_adaptive_yield

• Description: DBOptions::enable_write_thread_adaptive_yield for RocksDB.

• Command line: --rocksdb-enable-write-thread-adaptive-yield={0|1}

• Scope: Global

• Dynamic: No

rocksdb_error_if_exists

• Description: DBOptions::error_if_exists for RocksDBB.

• Command line: --rocksdb-error-if-exists={0|1}

• Scope: Global

• Dynamic: No

rocksdb_error_on_suboptimal_collation

• Description: Raise an error instead of warning if a sub-optimal collation is used.

• Command line: --rocksdb-error-on-suboptimal-collation={0|1}

• Scope: Global

• Dynamic: No

rocksdb_flush_log_at_trx_commit

• Description: Sync on transaction commit. Similar to . One can check the flushing by examining the and status variables.

  • 1: Always sync on commit (the default).

  • 0: Never sync.

  • 2: Sync based on a timer controlled via rocksdb-background-sync.

rocksdb_flush_memtable_on_analyze

• Description: Forces memtable flush on ANALZYE table to get accurate cardinality.

• Command line: --rocksdb-flush-memtable-on-analyze={0|1}

• Scope: Global, Session

• Dynamic: Yes

rocksdb_force_compute_memtable_stats

• Description: Force to always compute memtable stats.

• Command line: --rocksdb-force-compute-memtable-stats={0|1}

• Scope: Global

• Dynamic: Yes

rocksdb_force_compute_memtable_stats_cachetime

• Description: Time in usecs to cache memtable estimates.

• Command line: --rocksdb-force-compute-memtable-stats-cachetime=#

• Scope: Global

• Dynamic: Yes

rocksdb_force_flush_memtable_and_lzero_now

• Description: Acts similar to force_flush_memtable_now, but also compacts all L0 files.

• Command line: --rocksdb-force-flush-memtable-and-lzero-now={0|1}

• Scope: Global

• Dynamic: Yes

rocksdb_force_flush_memtable_now

• Description: Forces memstore flush which may block all write requests so be careful.

• Command line: --rocksdb-force-flush-memtable-now={0|1}

• Scope: Global

• Dynamic: Yes

rocksdb_force_index_records_in_range

• Description: Used to override the result of records_in_range() when is used.

• Command line: --rocksdb-force-index-records-in-range=#

• Scope: Global, Session

• Dynamic: Yes

rocksdb_git_hash

• Description: Git revision of the RocksDB library used by MyRocks.

• Command line: --rocksdb-git-hash=value=#

• Scope: Global

• Dynamic: No

rocksdb_hash_index_allow_collision

• Description: BlockBasedTableOptions::hash_index_allow_collision for RocksDB.

• Command line: --rocksdb-hash-index-allow-collision={0|1}

• Scope: Global

• Dynamic: No

rocksdb_ignore_unknown_options

• Description: Enable ignoring unknown options passed to RocksDB.

• Command line: --rocksdb-ignore-unknown-options={0|1}

• Scope: Global

• Dynamic: No

rocksdb_index_type

• Description: BlockBasedTableOptions::index_type for RocksDB.

• Command line: --rocksdb-index-type=value

• Scope: Global

• Dynamic: No

rocksdb_info_log_level

• Description: Filter level for info logs to be written mysqld error log. Valid values include 'debug_level', 'info_level', 'warn_level', 'error_level' and 'fatal_level'.

• Command line: --rocksdb-info-log-level=value

• Scope: Global

• Dynamic: Yes

rocksdb_io_write_timeout

• Description: Timeout for experimental I/O watchdog.

• Command line: --rocksdb-io-write-timeout=#

• Scope: Global

• Dynamic: Yes

rocksdb_is_fd_close_on_exec

• Description: DBOptions::is_fd_close_on_exec for RocksDB.

• Command line: --rocksdb-is-fd-close-on-exec={0|1}

• Scope: Global

• Dynamic: No

rocksdb_keep_log_file_num

• Description: DBOptions::keep_log_file_num for RocksDB.

• Command line: --rocksdb-keep-log-file-num=#

• Scope: Global

• Dynamic: No

rocksdb_large_prefix

• Description: Support large index prefix length of 3072 bytes. If off, the maximum index prefix length is 767.

• Command line: --rocksdb-large_prefix={0|1}

• Scope: Global

• Dynamic: Yes

rocksdb_lock_scanned_rows

• Description: Take and hold locks on rows that are scanned but not updated.

• Command line: --rocksdb-lock-scanned-rows={0|1}

• Scope: Global, Session

• Dynamic: Yes

rocksdb_lock_wait_timeout

• Description: Number of seconds to wait for lock.

• Command line: --rocksdb-lock-wait-timeout=#

• Scope: Global, Session

• Dynamic: Yes

rocksdb_log_dir

• Description: DBOptions::log_dir for RocksDB. Where the log files are stored. An empty value implies rocksdb_datadir is used as the directory.

• Command line: --rocksdb-log-dir=#

• Scope: Global

• Dynamic: No

rocksdb_log_file_time_to_roll

• Description: DBOptions::log_file_time_to_roll for RocksDB.

• Command line: --rocksdb-log-file-time-to_roll=#

• Scope: Global

• Dynamic: No

rocksdb_manifest_preallocation_size

• Description: DBOptions::manifest_preallocation_size for RocksDB.

• Command line: --rocksdb-manifest-preallocation-size=#

• Scope: Global

• Dynamic: No

rocksdb_manual_compaction_threads

• Description: How many rocksdb threads to run for manual compactions.

• Command line: --rocksdb-manual-compation-threads=#

• Scope: Global, Session

• Dynamic: Yes

rocksdb_manual_wal_flush

• Description: DBOptions::manual_wal_flush for RocksDB.

• Command line: --rocksdb-manual-wal-flush={0|1}

• Scope: Global

• Dynamic: No

rocksdb_master_skip_tx_api

• Description: Skipping holding any lock on row access. Not effective on slave.

• Command line: --rocksdb-master-skip-tx-api={0|1}

• Scope: Global, Session

• Dynamic: Yes

rocksdb_max_background_compactions

• Description: DBOptions::max_background_compactions for RocksDB.

• Command line: --rocksdb-max-background-compactions=#

• Scope: Global

• Dynamic: Yes

rocksdb_max_background_flushes

• Description: DBOptions::max_background_flushes for RocksDB.

• Command line: --rocksdb-max-background-flushes=#

• Scope: Global

• Dynamic: No

rocksdb_max_background_jobs

• Description: DBOptions::max_background_jobs for RocksDB.

• Command line: --rocksdb-max-background-jobs=#

• Scope: Global

• Dynamic: Yes

rocksdb_max_latest_deadlocks

• Description: Maximum number of recent deadlocks to store.

• Command line: --rocksdb-max-latest-deadlocks=#

• Scope: Global

• Dynamic: Yes

rocksdb_max_log_file_size

• Description: DBOptions::max_log_file_size for RocksDB.

• Command line: --rocksdb-max-log-file-size=#

• Scope: Global

• Dynamic: No

rocksdb_max_manifest_file_size

• Description: DBOptions::max_manifest_file_size for RocksDB.

• Command line: --rocksdb-manifest-log-file-size=#

• Scope: Global

• Dynamic: No

rocksdb_max_manual_compactions

• Description: Maximum number of pending + ongoing number of manual compactions..

• Command line: --rocksdb-manual_compactions=#

• Scope: Global

• Dynamic: Yes

rocksdb_max_open_files

• Description: DBOptions::max_open_files for RocksDB.

• Command line: --rocksdb-max-open-files=#

• Scope: Global

• Dynamic: No

rocksdb_max_row_locks

• Description: Maximum number of locks a transaction can have.

• Command line: --rocksdb-max-row-locks=#

• Scope: Global, Session

• Dynamic: Yes

rocksdb_max_subcompactions

• Description: DBOptions::max_subcompactions for RocksDB.

• Command line: --rocksdb-max-subcompactions=#

• Scope: Global

• Dynamic: No

rocksdb_max_total_wal_size

• Description: DBOptions::max_total_wal_size for RocksDB. The maximum size limit for write-ahead-log files. Once this limit is reached, RocksDB forces the flushing of memtables.

• Command line: --rocksdb-max-total-wal-size=#

• Scope: Global

• Dynamic: No

rocksdb_merge_buf_size