[3.0] Puts an index prefix length outside the column's quoting

[albertlast]

Description

On MySQL, table_sql() returns SQL that MySQL will not accept for any table carrying an index on part of a column:

ERROR 1072 (42000): Key column 'member_groups(48)' doesn't exist in table

A column can be indexed by its first so many characters, and list_indexes() reports that the way MySQL states it, as member_groups(48). table_sql() then quotes each index column whole:

$line .= ' (`' . implode('`, `', $index['columns']) . '`)';

which puts the count inside the name and asks for a column called member_groups(48). What MySQL wants is `member_groups`(48), with the count outside the quoting.

Twelve indexes on a forum with nothing added to it are affected, and two of them are primary keys:

table	index	column
admin_info_files	idx_filename	filename(191)
boards	idx_member_groups	member_groups(191)
log_packages	filename, idx_filename, idx_hash	filename(191), filename(15), sha256_hash(191)
members	idx_active_real_name, idx_email_address_ci, idx_lngfile, idx_spoofdetector_name, idx_spoofdetector_name_id	real_name(191), email_address_ci(191), lngfile(30), spoofdetector_name(191)
settings	PRIMARY	variable(191)
themes	PRIMARY	variable(191)

Nothing in SMF calls table_sql(), which is why this has gone unnoticed. It is public API, reachable through the db_table_sql alias in DatabaseApi::$db_function_map, so a mod using it to record or copy a table gets SQL it cannot run.

PostgreSQL is unaffected: its table_sql() asks the server for each index with pg_get_indexdef() rather than assembling one.

How this was verified

Against a MySQL forum upgraded from the 2.1.7 baseline, by taking Db::$db->table_sql('smf_boards') and running it into an empty database, which is the only thing the output is for:

	before	after
replaying the output	ERROR 1072, no table created	runs, exit 0
rebuilt table vs the original	—	columns and keys identical

The comparison is SHOW CREATE TABLE on both, with AUTO_INCREMENT= removed since it records how many rows a table has held rather than its shape.

Not reachable from the unit suite

table_sql() is a database driver method and needs a connection.

Issues References (Fixes|Related|Closes)

1. Related: [3.0] Lets table_sql read a column that has no default #9651, the same method failing on PostgreSQL for a different reason.