MDEV-19191 Partial support of foreign keys in partitioned tables #3513

When there are GCC-incompatible compiler flags dtrace fails like this: gcc: error: unrecognized command-line option ‘-fno-limit-debug-info’ gcc: error: unrecognized command-line option ‘-mbranches-within-32B-boundaries’ "gcc .dtrace-temp.3fd6bacf.c" failed Usage /usr/bin/dtrace [--help] [-h | -G] [-C [-I<Path>]] -s File.d [-o <File>]

Return true for temporary partitions.

Based on Marko Makela's patch 4a591d4: dict_get_referenced_table(): Let the caller convert names when needed. row_rename_table_for_mysql(): Specify the treatment of FOREIGN KEY constraints in a 4-valued enum parameter. In cases where FOREIGN KEY constraints cannot exist (partitioned tables, or internal tables of FULLTEXT INDEX), we can use the mode RENAME_IGNORE_FK. The mod RENAME_REBUILD is for any DDL operation that rebuilds the table inside InnoDB, such as TRUNCATE and native ALTER TABLE (or OPTIMIZE TABLE). The mode RENAME_ALTER_COPY is used solely during non-native ALTER TABLE in ha_innobase::rename_table(). Normal ha_innobase::rename_table() will use the mode RENAME_FK. CREATE OR REPLACE will rename the old table (if one exists) along with its FOREIGN KEY constraints into a temporary name. The replacement table will be initially created with another temporary name. Unlike in ALTER TABLE, all FOREIGN KEY constraints must be renamed and not inherited as part of these operations, using the mode RENAME_FK. dict_get_referenced_table(): Let the callers convert names when needed. create_table_info_t::create_foreign_keys(): CREATE OR REPLACE creates the replacement table with a temporary name table, so for self-references foreign->referenced_table will be a table with temporary name and charset conversion must be skipped for it.

All InnoDB internal SQL functions should be moved to sql_funcs.h

Use temporary constraint names for temporary tables. The constraints are not added to cache (skipped in dict_table_rename_in_cache()). The scheme for temporary constraint names is as follows: for old table: db_name/\xFFconstraint_name for new table: db_name/\xFF\xFFconstraint_name normalize_table_name_c_low(): wrong comparison "less than FN_REFLEN - 1". Somewhere array of FN_REFLEN includes the trailing 0, somewhere array of FN_REFLEN + 1 includes trailing 0, but nowhere array of FN_REFLEN - 1 must include trailing 0. Change from original MDEV-28933 fix: As temporary FK is now required for any ALTER operation (especially partitioning operations) row_rename_table_for_mysql() does FK rename on both RENAME_FK and RENAME_ALTER_COPY (see do_rename_fk).

The patch adds the ability to run foreign keys in partitioned tables with limitations. Example: create or replace table t1 (id int primary key) engine innodb; create or replace table t2 (fk int references t1(id)) engine innodb partition by hash (fk) partitions 2; Limitations: 1. Foreign keys cannot refer partitioned table even SYSTEM_TIME-partitioned still. create_foreign_keys() at InnoDB layer receives Foreign_key about referenced table T, but no such table exists in InnoDB layer, only partition tables T#P#p0, T#P#p1, ..., T#P#pn. Finding out it is SYSTEM_TIME partitioning and current partition at that point is impossible without modification of SYS_TABLES or opening TABLE object of referenced table. Both should be avoided as this is superseded by MDEV-12483. 2. CASCADE and SET NULL actions are disabled in partitioned foreign table as these actions update row data and this is the subject of row placement into another partition but it cannot be done in InnoDB layer. DELETE CASCADE for SYSTEM_TIME partitioning requires the row to be moved from current to history partition. The task is basically divided into 3 parts: 1. Remove prohibiting code, allow FKs to be created for partitions; 2. Allow partitioned FKs at SQL layer for such functions as SHOW CREATE; 3. Implement correct handling of FKs when partitioning configuration changes. 1. Remove prohibiting code, allow FKs to be created for partitions In SYS_FOREIGN table foreign key records are unique by ID which was taken from constraint name or automatically generated. Normally foreign ID and constraint name are identical, but that's not the case for partitioned table as InnoDB holds foreign keys per dict_table_t object and each partition is a different table for InnoDB. So for each foreign key in SQL layer there is a set of foreign keys in InnoDB layer per each partition (except SYSTEM_TIME partitioning where we keep foreign keys only for current partition). To constitute unique foreign ID at InnoDB layer we concatenate constraint name with partition suffix, the one what is added to partition table name beginning with #P# and optionally containing #SP# for subpartitions. Constraint name and partitioning suffix are separated by \xFF character which is the safe character code non-clashing with identifier character set. When we return back foreign ID to SQL layer this partitioning suffix is stripped off the constraint name and SQL output receives the name similar to non-partitioned table. User may see a bit more truthful version of foreign ID in INFORMATION_SCHEMA.INNODB_SYS_FOREIGN with \xFF replaced by ':' and #P# or everything starting from #P# and ending by #SP# chopped out. So he may see corresponding partition name or subpartition name in ID of INNODB_SYS_FOREIGN. 2. Allow partitioned FKs at SQL layer for such functions as SHOW CREATE Through standard handler interface get_foreign_key_list() foreign keys are returned to SQL layer. For SYSTEM_TIME partitioning from current partition, for any other partitioning from first read-marked partition. 3. Implement correct handling of FKs when partitioning configuration changes ALTER operations such as ADD PARTITION, DROP PARTITION, REMOVE PARTITIONING, etc. are reflected into correct configuration of foreign keys in InnoDB. Handling of foreign key ID for temporary tables in ALTER was done based on MDEV-28933.

This commit is not intended to be pushed into main branch. Its mission is to simplify the review process. The comments here are in different style: // and without indentation. The reviewer may ask for some of them to be included into the task code. In that case they will be reformatted and moved to the task commit.

Related to FIXME here. Now check_bulk_buffer() returns false. 3389 if (auto t= trx->check_bulk_buffer(index->table)) { 3390 /* MDEV-25036 FIXME: 3391 row_ins_check_foreign_constraint() check 3392 should be done before buffering the insert 3393 operation. */ 3394 ut_ad(index->table->skip_alter_undo 3395 || !trx->check_foreigns); 3396 return t->bulk_insert_buffered(*entry, *index, trx); 3397 }

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MDEV-19191 Partial support of foreign keys in partitioned tables #3513

MDEV-19191 Partial support of foreign keys in partitioned tables #3513

Commits on Sep 11, 2024

MDEV-19191 Partial support of foreign keys in partitioned tables #3513

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MDEV-19191 Partial support of foreign keys in partitioned tables #3513

Commits on Sep 11, 2024