Overview

MariaDB Enterprise ColumnStore supports very efficient bulk data loads.

MariaDB Enterprise ColumnStore performs bulk data loads very efficiently using a variety of mechanisms, including the cpimport tool, specialized handling of certain SQL statements, and minimal locking during data import.

cpimport

MariaDB Enterprise ColumnStore includes a bulk data loading tool called cpimport, which provides several benefits:

• Bypasses the SQL layer to decrease overhead

• Does not block read queries

• Requires a write metadata lock on the table, which can be monitored with the

• Appends the new data to the table. While the bulk load is in progress, the newly appended data is temporarily hidden from queries. After the bulk load is complete, the newly appended data is visible to queries.

Batch Insert Mode

MariaDB Enterprise ColumnStore enables batch insert mode by default.

When batch insert mode is enabled, MariaDB Enterprise ColumnStore has special handling for the following statements:

• [[|load-data-infileLOAD DATA [ LOCAL ] INFILE]]

Enterprise ColumnStore uses the following rules:

• If the statement is executed outside of a transaction, Enterprise ColumnStore loads the data using cpimport, which is a command-line utility that is designed to efficiently load data in bulk. It executes cpimport using a wrapper called cpimport.bin.

• If the statement is executed inside of a transaction, Enterprise ColumnStore loads the data using the DML interface, which is slower.

Batch insert mode can be disabled by setting the columnstore_use_import_for_batchinsert system variable to OFF. When batch insert mode is disabled, Enterprise ColumnStore executes the statements using the DML interface, which is slower.

Locking

MariaDB Enterprise ColumnStore requires a write metadata lock (MDL) on the table when a bulk data load is performed with cpimport.

When a bulk data load is running:

• Read queries will not be blocked.

• Write queries and concurrent bulk data loads on the same table will be blocked until the bulk data load operation is complete, and the write metadata lock on the table has been released.

• The write metadata lock (MDL) can be monitored with the .

Choose a Data Load Method

Overview

MariaDB Enterprise ColumnStore includes a stored procedure called columnstore_info.load_from_s3, which can load data from a plain-text file containing delimiter-separated values (such as CSV or TSV) stored on S3-compatible cloud object storage.

Compatibility

Available from MariaDB Enterprise ColumnStore 23.02.

System Variables

Before you import data with the columnstore_info.load_from_s3 stored procedure, the authentication credentials and the region can be configured using system variables:

• columnstore_s3_key

• columnstore_s3_secret

• columnstore_s3_region

For example, the following statements show how to set the system variables for your current session:

Import Data

To import data with the columnstore_info.load_from_s3 stored procedure, use the CALL statement:

• Replace 'BUCKET_URL' with the URL of your bucket. The protocol in the URL must be s3: for AWS S3 or gs: for Google Cloud Storage

• Replace 'FILE_NAME' with the file name to load from. The file must be a plain-text file containing delimiter-separated values, such as a comma-separated values (CSV) or tab-separated values (TSV) file. The supported file format is similar to the plain-text file formats supported by cpimport and LOAD DATA [LOCAL] INFILE. Please note that this stored procedure can't load dump files created by mariadb-dump

All parameters are mandatory.

For example, to load a comma-separated values (CSV) file from AWS S3:

When the stored procedure completes, it returns JSON containing the status of the operation. If the JSON shows an error or "success": false, check your table to see if some or all of your data was loaded, because many errors are non-fatal.

Permissions

When the data file is stored in Amazon S3, the AWS user only requires the s3:GetObject action on the bucket.

For example, the AWS user can use a user policy like the following:

Overview

MariaDB Enterprise ColumnStore automatically translates INSERT INTO .. SELECT FROM .. statements into bulk data loads. By default, it translates the statement into a bulk data load that uses cpimport.bin, which is an internal wrapper around the cpimport tool.

Overview

MariaDB Enterprise ColumnStore automatically translates LOAD DATA [ LOCAL ] INFILE statements into bulk data loads. By default, it translates the statement into a bulk data load that uses cpimport.bin, which is an internal wrapper around the cpimport tool.

Intended Use Cases

You can load data using the statement in the following cases:

• You are loading data into a ColumnStore table from a text file stored on the primary node's file system.

• You are loading data into a ColumnStore table from a text file stored on the client's file system. In this case, LOAD DATA LOCAL INFILE must be used.

Batch Insert Mode

MariaDB Enterprise ColumnStore enables batch insert mode by default.

When batch insert mode is enabled, MariaDB Enterprise ColumnStore has special handling for statements.

Enterprise ColumnStore uses the following rules:

• If the statement is executed outside of a transaction, Enterprise ColumnStore loads the data using , which is a command-line utility that is designed to efficiently load data in bulk. Enterprise ColumnStore executes cpimport using a wrapper called cpimport.bin.

• If the statement is executed inside of a transaction, Enterprise ColumnStore loads the data using the DML interface, which is slower.

Batch insert mode can be disabled by setting the columnstore_use_import_for_batchinsert system variable to OFF. When batch insert mode is disabled, Enterprise ColumnStore executes the statements using the DML interface, which is slower.

Insert Cache

Starting with MariaDB Enterprise ColumnStore 6, an insert cache can be enabled to speed up statements.

The insert cache is disabled by default, but it can be enabled by configuring columnstore_cache_inserts=ON:

The cache is flushed to ColumnStore in the following scenarios:

When the number of cached rows exceeds the value of columnstore_cache_flush_threshold

When a statement other than or is executed, is used to flush the insert cache to ColumnStore when columnstore_cache_use_import=ON is configured.

Locking

MariaDB Enterprise ColumnStore requires a write metadata lock (MDL) on the table when a bulk data load is performed with .

When a bulk data load is running:

• Read queries will not be blocked.

• Write queries and concurrent bulk data loads on the same table will be blocked until the bulk data load operation is complete, and the write metadata lock on the table has been released.

• The write metadata lock (MDL) can be monitored with the .

Importing the Schema

Before data can be imported into the tables, the schema must be created.

1. Connect to the primary server using :

After the command is executed, it will prompt you for a password.

1. For each database that you are importing, create the database with the statement:

For each table that you are importing, create the table with the statement:

Appending Data

When MariaDB Enterprise ColumnStore performs a bulk data load, it appends data to the table in the order in which the data is read. Appending data reduces the I/O requirements of bulk data loads, so that larger data sets can be loaded very efficiently.

While the bulk load is in progress, the newly appended data is temporarily hidden from queries.

After the bulk load is complete, the newly appended data is visible to queries.

Sorting the Input File

When MariaDB Enterprise ColumnStore performs a bulk data load, it appends data to the table in the order in which the data is read.

The order of data can have a significant effect on performance with Enterprise ColumnStore, so it can be helpful to sort the data in the input file prior to importing it.

For additional information, see "".

Confirming the Field Delimiter

Before importing a file into MariaDB Enterprise ColumnStore, confirm that the field delimiter is not present in the data.

The field delimiter is determined by the columnstore_import_for_batchinsert_delimiter system variable. By default, Enterprise ColumnStore sets the field delimiter to the ASCII value 7, which corresponds to the BEL character.

To use another delimiter, you can set the field delimiter.

Loading a Local Input File on the Client

If you are loading a file located on the client, you can use the statement. However, for this statement to work, the client must explicitly enable usage of a local infile.

If you are using the --local-infile option can be used:

If you are using , the MYSQL_OPT_LOCAL_INFILE option can be set with the mysql_optionsv() function:

If you are using , the allowLocalInfile parameter can be set for the connection:

If you are using , the permitLocalInfile parameter can be set for the connection:

If you are using , the local_infile parameter can be set for the connection:

The default field delimiter for the statement is a tab.

If your data file uses a different field delimiter, you can specify the field delimiter with the FIELDS TERMINATED BY clause.

To load a TSV (tab-separated values) file:

Setting the Quoting Style

By default, the statement does not expect fields to be quoted.

If your data file uses quotes around fields, you can specify the quote character with the FIELDS [OPTIONALLY] ENCLOSED BY clause.

To load a TSV (tab-separated values) file that uses double quotes:

Limitations

MariaDB Enterprise ColumnStore ignores the ON DUPLICATE KEY clause.

Ensure that duplicate data is removed prior to performing a bulk data load.

Overview

MariaDB Enterprise ColumnStore includes a bulk data loading tool called cpimport, which bypasses the SQL layer to decrease the overhead of bulk data loading.

Refer to the cpimport modes for additional information and to ColumnStore Bulk Data Loading.

The cpimport tool:

• Bypasses the SQL layer to decrease overhead;

• Does not block read queries;

• Requires a write metadata lock on the table, which can be monitored with the ;

• Appends the new data to the table. While the bulk load is in progress, the newly appended data is temporarily hidden from queries. After the bulk load is complete, the newly appended data is visible to queries;

• Inserts each row in the order the rows are read from the source file. Users can optimize data loads for Enterprise ColumnStore's automatic partitioning by loading presorted data files;

• Supports parallel distributed bulk loads;

• Imports data from text files;

• Imports data from binary files;

• Imports data from standard input (stdin).

Intended Use Cases

You can load data using the cpimport tool in the following cases:

• You are loading data into a ColumnStore table from a text file stored on the primary node's file system.

• You are loading data into a ColumnStore table from a binary file stored on the primary node's file system.

• You are loading data into a ColumnStore table from the output of a command running on the primary node.

Locking

MariaDB Enterprise ColumnStore requires a write metadata lock (MDL) on the table when a bulk data load is performed with cpimport.

When a bulk data load is running:

• Read queries will not be blocked.

• Write queries and concurrent bulk data loads on the same table will be blocked until the bulk data load operation is complete, and the write metadata lock on the table has been released.

• The write metadata lock (MDL) can be monitored with the .

Importing the Schema

Before data can be imported into the tables, the schema must be created.

1. Connect to the primary server using :

After the command is executed, it prompts for a password.

1. For each imported database, create the database with the statement:

1. For each imported table, create the table with the statement:

Appending Data

When MariaDB Enterprise ColumnStore performs a bulk data load, it appends data to the table in the order in which the data is read. Appending data reduces the I/O requirements of bulk data loads, so that larger data sets can be loaded very efficiently.

While the bulk load is in progress, the newly appended data is temporarily hidden from queries.

After the bulk load is complete, the newly appended data is visible to queries.

Sorting the Input File

When MariaDB Enterprise ColumnStore performs a bulk data load, it appends data to the table in the order in which the data is read.

The order of data can have a significant effect on performance with Enterprise ColumnStore, so it can be helpful to sort the data in the input file prior to importing it.

For additional information, see "".

Confirming the Field Delimiter

Before importing a file into MariaDB Enterprise ColumnStore, confirm that the field delimiter is not present in the data.

The default field delimiter for the cpimport tool is a pipe (|).

To use a different delimiter, you can set the field delimiter.

Importing from Text Files

The cpimport tool can import data from a text file if a file is provided as an argument after the database and table name.

For example, to import the file inventory-products.txt into the products table in the inventory database:

Importing from Binary Files

The cpimport tool can import data from a binary file if the -I1 or -I2 option is provided and a file is provided as an argument after the database and table name.

For example, to import the file inventory-products.bin into the products table in the inventory database:

The -I1 and -I2 options allow two different binary import modes to be selected:

The binary file should use the following format for data:

Binary DATE Format

In binary input files, the cpimport tool expects columns to be in the following format:

Binary DATETIME Format

In binary input files, the cpimport tool expects columns to be in the following format:

Importing from Standard Input

The cpimport tool can import data from standard input (stdin) if no file is provided as an argument.

Importing from standard input is useful in many scenarios.

One scenario is when you want to import data from a remote database. You can use to query the table using the statement, and then pipe the results into the standard input of the cpimport tool:

Importing from S3 Using AWS CLI

The cpimport tool can import data from a file stored in a remote S3 bucket.

You can use the AWS CLI to copy the file from S3, and then pipe the contents into the standard input of the cpimport tool:

Alternatively, the columnstore_info.load_from_s3 stored procedure can import data from S3-compatible cloud object storage.

Setting the Field Delimiter

The default field delimiter for the cpimport tool is a pipe sign (|).

If your data file uses a different field delimiter, you can specify the field delimiter with the -s option.

For a TSV (tab-separated values) file:

For a CSV (comma-separated values) file:

Setting the Quoting Style

By default, the cpimport tool does not expect fields to be quoted.

If your data file uses quotes around fields, you can specify the quote character with the -E option.

To load a TSV (tab-separated values) file that uses double quotes:

To load a CSV (comma-separated values) file that uses optional single quotes:

Logging

The cpimport tool writes logs to different directories, depending on the Enterprise ColumnStore version:

• In Enterprise ColumnStore 5.5.2 and later, logs are written to /var/log/mariadb/columnstore/bulk/

• In Enterprise ColumnStore 5 releases before 5.5.2, logs are written to /var/lib/columnstore/data/bulk/

• In Enterprise ColumnStore 1.4, logs are written to /usr/local/mariadb/columnstore/bulk/

Special Handling

Column Order

The cpimport tool requires column values to be in the same order in the input file as the columns in the table definition.

Date Format

The cpimport tool requires values to be specified in the format YYYY-MM-DD.

Transaction Log

The cpimport tool does not write bulk data loads to the transaction log, so they are not transactional.

Binary Log

The cpimport tool does not write bulk data loads to the binary log, so they cannot be replicated using .

EFS Storage

When Enterprise ColumnStore uses object storage and the Storage Manager directory uses EFS in the default Bursting Throughput mode, the cpimport tool can have performance problems if multiple data load operations are executed consecutively. The performance problems can occur because the Bursting Throughput mode scales the rate relative to the size of the file system, so the burst credits for a small Storage Manager volume can be fully consumed very quickly.

When this problem occurs, some solutions are:

• Avoid using burst credits by using Provisioned Throughput mode instead of Bursting Throughput mode

• Monitor burst credit balances in AWS and run data load operations when burst credits are available

• Increase the burst credit balance by increasing the file system size (for example, by creating a dummy file)

Additional information is available .