Webinar | Multcloud Disaster Recovery with MariaDB
Watch Now
Ctrlk
Download MariaDBContact Us
For the complete documentation index, see llms.txt. This page is also available as Markdown.
Edit

TideSQL System Variables

A complete reference for TideSQL system variables, grouped by scope: flush and compaction pool, block cache, memtable, durability, full-text search, and per- session table-option defaults.

This page documents system variables related to the TideSQL storage engine. The read-only group is set at server startup and cannot change while the server runs. The dynamic global group can be changed at runtime with SET GLOBAL. The session group can be set per connection with SET SESSION, and its global value is the default that new sessions inherit.

Global, Read-Only Variables

These variables are set at server startup and cannot be changed while the server runs.

tidesdb_flush_threads

  • Description: Background threads flushing memtables to SSTables. 0 lets the library auto-size the shared flush pool to min(CPU count, 4) at open.

  • Command line: --tidesdb-flush-threads=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: 4

tidesdb_compaction_threads

  • Description: Background threads running LSM compaction.

  • Command line: --tidesdb-compaction-threads=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: 4

tidesdb_log_level

  • Description: Library log level.

  • Command line: --tidesdb-log-level=value

  • Scope: Global

  • Dynamic: No

  • Data Type: enumeration

  • Default Value: TRACE

  • Valid Values: TRACE, INFO, WARN, ERROR, NONE

tidesdb_block_cache_size

  • Description: Size in bytes of the global block cache shared across all column families.

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

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: 268435456 (256 MB)

tidesdb_max_open_sstables

  • Description: Maximum SSTable structures cached in the LRU. 0 means unlimited, bounded only by the process open-file limit.

  • Command line: --tidesdb-max-open-sstables=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: 256

tidesdb_log_to_file

  • Description: Write library logs to a LOG file in the data directory instead of stderr.

  • Command line: --tidesdb-log-to-file={0|1}

  • Scope: Global

  • Dynamic: No

  • Data Type: boolean

  • Default Value: ON

tidesdb_log_truncation_at

  • Description: Log file truncation size in bytes. 0 disables truncation.

  • Command line: --tidesdb-log-truncation-at=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: 25165824 (24 MB)

tidesdb_memtable_write_buffer_size

  • Description: Write buffer size in bytes for the shared memtable. 0 lets the library auto-size it.

  • Command line: --tidesdb-memtable-write-buffer-size=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: 268435456 (256 MB)

tidesdb_memtable_sync_mode

  • Description: WAL durability for every commit. See Durability and Sync Modes.

  • Command line: --tidesdb-memtable-sync-mode=value

  • Scope: Global

  • Dynamic: No

  • Data Type: enumeration

  • Default Value: FULL

  • Valid Values: NONE, INTERVAL, FULL

tidesdb_memtable_sync_interval

  • Description: WAL sync interval in microseconds, used only when the sync mode is INTERVAL.

  • Command line: --tidesdb-memtable-sync-interval=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: 128000

tidesdb_memtable_skip_list_max_level

  • Description: Skip-list max level for the memtable. 0 keeps the library default.

  • Command line: --tidesdb-memtable-skip-list-max-level=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: 0

tidesdb_memtable_skip_list_probability

  • Description: Skip-list level-promotion probability for the memtable. 0.0 keeps the library default.

  • Command line: --tidesdb-memtable-skip-list-probability=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: 0.0

tidesdb_vlog_segment_size

  • Description: Size in bytes at which the value log seals a segment and opens a fresh one. 0 keeps the library default.

  • Command line: --tidesdb-vlog-segment-size=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: 0

tidesdb_value_separation_threshold

  • Description: Values at or above this size in bytes go to the shared value log instead of inline in the klog, so compaction rewrites only a reference. Database-wide, applied at open. 0 keeps the library default.

  • Command line: --tidesdb-value-separation-threshold=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: 0

tidesdb_memtable_l0_queue_stall_threshold

  • Description: Sealed-memtable queue depth at which writes are paced for back-pressure. 0 keeps the library default of 16.

  • Command line: --tidesdb-memtable-l0-queue-stall-threshold=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: 0

tidesdb_memtable_idle_flush_seconds

  • Description: Seconds of write inactivity after which the shared memtable is flushed even before it fills. -1 keeps the library default.

  • Command line: --tidesdb-memtable-idle-flush-seconds=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: -1

tidesdb_txn_timeout_seconds

  • Description: Seconds a transaction may run before the library aborts it. -1 keeps the library default.

  • Command line: --tidesdb-txn-timeout-seconds=#

  • Scope: Global

  • Dynamic: No

  • Data Type: numeric

  • Default Value: -1

tidesdb_data_home_dir

  • Description: Directory for the data files.

  • Command line: --tidesdb-data-home-dir=path

  • Scope: Global

  • Dynamic: No

  • Data Type: directory name

  • Default Value: <mysql_datadir>/../tidesdb_data

Global, Dynamic Variables

These variables are global and can be changed at runtime with SET GLOBAL.

tidesdb_backup_dir

  • Description: Set to a path to trigger an online backup. Clear with an empty string. See Backup and Checkpoint.

  • Command line: --tidesdb-backup-dir=path

  • Scope: Global

  • Dynamic: Yes

  • Data Type: directory name

  • Default Value: (empty)

tidesdb_checkpoint_dir

  • Description: Set to a path to write a consistent checkpoint copy of the data directory there, a durable flush of the WAL, value log, and manifest followed by a byte-for-byte copy. Clear with an empty string.

  • Command line: --tidesdb-checkpoint-dir=path

  • Scope: Global

  • Dynamic: Yes

  • Data Type: directory name

  • Default Value: (empty)

tidesdb_fts_min_word_len

  • Description: Minimum word length in characters for full-text indexing.

  • Command line: --tidesdb-fts-min-word-len=#

  • Scope: Global

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 3

tidesdb_fts_max_word_len

  • Description: Maximum word length in characters for full-text indexing.

  • Command line: --tidesdb-fts-max-word-len=#

  • Scope: Global

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 84

tidesdb_fts_bm25_k1

  • Description: BM25 k1 parameter, term-frequency saturation.

  • Command line: --tidesdb-fts-bm25-k1=#

  • Scope: Global

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 1.2

tidesdb_fts_bm25_b

  • Description: BM25 b parameter, document-length normalization.

  • Command line: --tidesdb-fts-bm25-b=#

  • Scope: Global

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 0.75

  • Range: 0 to 1

tidesdb_fts_blend_chars

  • Description: Characters treated as both separators and word characters. Set to ' for Italian and French elision. See Full-Text Search.

  • Command line: --tidesdb-fts-blend-chars=value

  • Scope: Global

  • Dynamic: Yes

  • Data Type: string

  • Default Value: (empty)

tidesdb_ft_stopword_table

  • Description: Custom stop-word table in db_name/table_name form. NULL uses the InnoDB default list, empty string disables stop-word filtering.

  • Command line: --tidesdb-ft-stopword-table=value

  • Scope: Global

  • Dynamic: Yes

  • Data Type: string

  • Default Value: NULL

Session Variables With a Global Default

These variables are session-scoped. Setting one globally changes the default that new sessions inherit. The tidesdb_default_* group supplies the default for the matching table option when CREATE TABLE does not set it.

tidesdb_ttl

  • Description: Per-session TTL in seconds applied to INSERT and UPDATE. 0 uses the table default. Works with SET SESSION and SET STATEMENT. See Time-To-Live.

  • Command line: --tidesdb-ttl=#

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 0

tidesdb_skip_unique_check

  • Description: Skip uniqueness checks on the primary key and unique secondary indexes during INSERT. Safe only when the application guarantees no duplicates.

  • Command line: --tidesdb-skip-unique-check={0|1}

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: boolean

  • Default Value: OFF

tidesdb_single_delete_primary

  • Description: Use single-delete semantics on the primary row column family for this session's DELETE statements.

  • Command line: --tidesdb-single-delete-primary={0|1}

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: boolean

  • Default Value: OFF

tidesdb_compact_after_range_delete_min_rows

  • Description: After a multi-row DELETE touching at least this many rows, compact the touched primary-key range synchronously. 0 disables it.

  • Command line: --tidesdb-compact-after-range-delete-min-rows=#

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 0

tidesdb_default_compression

  • Description: Default COMPRESSION for new tables.

  • Command line: --tidesdb-default-compression=value

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: enumeration

  • Default Value: LZ4

  • Valid Values: NONE, SNAPPY, LZ4, ZSTD, LZ4_FAST

tidesdb_default_bloom_filter

  • Description: Default BLOOM_FILTER for new tables.

  • Command line: --tidesdb-default-bloom-filter={0|1}

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: boolean

  • Default Value: ON

tidesdb_default_bloom_fpr

  • Description: Default BLOOM_FPR in parts per 10,000, 100 is 1%.

  • Command line: --tidesdb-default-bloom-fpr=#

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 100

tidesdb_default_keep_values_inline

  • Description: Default KEEP_VALUES_INLINE for new tables.

  • Command line: --tidesdb-default-keep-values-inline={0|1}

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: boolean

  • Default Value: OFF

tidesdb_default_btree_klog_block_size

  • Description: Default BTREE_KLOG_BLOCK_SIZE in bytes for new tables. Sizing a node to the block manager first-read window avoids a second read per access.

  • Command line: --tidesdb-default-btree-klog-block-size=#

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 4096

tidesdb_default_l1_file_count_trigger

  • Description: Default L1_FILE_COUNT_TRIGGER.

  • Command line: --tidesdb-default-l1-file-count-trigger=#

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 4

tidesdb_default_level_size_ratio

  • Description: Default LEVEL_SIZE_RATIO.

  • Command line: --tidesdb-default-level-size-ratio=#

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 10

tidesdb_default_min_levels

  • Description: Default MIN_LEVELS.

  • Command line: --tidesdb-default-min-levels=#

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 1

tidesdb_default_dividing_level_offset

  • Description: Default DIVIDING_LEVEL_OFFSET.

  • Command line: --tidesdb-default-dividing-level-offset=#

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 1

tidesdb_default_isolation_level

  • Description: Default ISOLATION_LEVEL. See Transactions and Isolation.

  • Command line: --tidesdb-default-isolation-level=value

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: enumeration

  • Default Value: REPEATABLE_READ

tidesdb_default_tombstone_density_trigger

  • Description: Default TOMBSTONE_DENSITY_TRIGGER in parts per 10,000, 0 disables it.

  • Command line: --tidesdb-default-tombstone-density-trigger=#

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 0

tidesdb_default_tombstone_density_min_entries

  • Description: Default TOMBSTONE_DENSITY_MIN_ENTRIES.

  • Command line: --tidesdb-default-tombstone-density-min-entries=#

  • Scope: Global, Session

  • Dynamic: Yes

  • Data Type: numeric

  • Default Value: 1024

Setting Defaults in my.cnf

This page is licensed: GPLv2

PreviousTideSQL Table Options
NextTideSQL Status Variables

Last updated

Was this helpful?