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https://dev.mysql.com/doc/refman/8.4/en/index-page-merge-threshold.html
row *************************** Table: t2 Create Table: CREATE TABLE `t2` ( `id` int(11) DEFAULT NULL, KEY `id_index` (`id`) COMMENT 'MERGE_THRESHOLD=40' ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci Note A MERGE_THRESHOLD value ...If the “page-full” percentage for an index page falls below the MERGE_THRESHOLD value when a row is deleted or when a row is shortened by an UPDATE operation, InnoDB attempts to merge the index page with a neighboring index ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-information-schema-system-tables.html
row *************************** TABLE_ID: 71 NAME: col1 POS: 0 MTYPE: 6 PRTYPE: 1027 LEN: 4 HAS_DEFAULT: 0 DEFAULT_VALUE: NULL *************************** 2. row *************************** TABLE_ID: 71 NAME: col2 POS: 1 MTYPE: 2 PRTYPE: 524542 LEN: ... You can extract metadata about schema objects managed by InnoDB using InnoDB INFORMATION_SCHEMA ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-troubleshooting-datadict.html
Information about table definitions is stored in the InnoDB data dictionary. If you move data files around, dictionary data can become inconsistent. If a data dictionary corruption or consistency issue prevents you from starting InnoDB, see Section ...
https://dev.mysql.com/doc/refman/8.4/en/insert.html
Warnings can occur under any of the following conditions: Inserting NULL into a column that has been declared NOT NULL. (For a single-row INSERT, no warning occurs when NULL is inserted into a NOT NULL column. INSERT [LOW_PRIORITY | DELAYED | ...
https://dev.mysql.com/doc/refman/8.4/en/locking-functions.html
Returns 1 if the lock was obtained successfully, 0 if the attempt timed out (for example, because another client has previously locked the name), or NULL if an error occurred (such as running out of memory or the thread was killed with mysqladmin ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-limitations-syntax.html
Using nullable columns in unique keys and primary keys means that queries using these columns are handled as full table scans. To work around this issue, make the column NOT NULL, or re-create the index without the USING HASH option. This means ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-operations-per-fragment.html
The operations_per_fragment table provides information about the operations performed on individual fragments and fragment replicas, as well as about some of the results from these operations. This currently has the following formats: Base table: ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-options-variables.html
ndb_conflict_role can take any one of the values PRIMARY, SECONDARY, PASS, or NULL (the default). row *************************** id: 1 select_type: SIMPLE table: d type: ALL possible_keys: PRIMARY key: NULL key_len: NULL ref: NULL rows: 9 Extra: ...
https://dev.mysql.com/doc/refman/8.4/en/optimizing-innodb-bulk-data-loading.html
For optimal performance when loading data into an InnoDB FULLTEXT index, follow this set of steps: Define a column FTS_DOC_ID at table creation time, of type BIGINT UNSIGNED NOT NULL, with a unique index named FTS_DOC_ID_INDEX. For example: CREATE ... These performance tips supplement the general guidelines for fast inserts in Section 10.2.5.1, “Optimizing INSERT ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-firewall-groups-table.html
The value is NULL, or a non-NULL account that has the format user_name@host_name: If the value is NULL, the firewall records allowlist rules for statements received from any account that is a member of the group. If the value is non-NULL, the ...