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Fix ON UPDATE CURRENT_TIMESTAMP for explicit values and unchanged rows #560

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Merged
adamziel merged 2 commits into from
Oct 23, 2026
Merged

Fix ON UPDATE CURRENT_TIMESTAMP for explicit values and unchanged rows #560

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359c484
Emulate ON UPDATE CURRENT_TIMESTAMP in UPDATE translation
JanJakes Oct 22, 2026
0a5f1db
Drop old ON UPDATE CURRENT_TIMESTAMP triggers on upgrade
JanJakes Oct 22, 2026
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131 changes: 87 additions & 44 deletions packages/mysql-on-sqlite/src/sqlite/class-wp-mysql-on-sqlite.php
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Original file line number Diff line number Diff line change
Expand Up @@ -2724,7 +2724,7 @@ private function execute_update_statement( WP_Parser_Node $node ): void {
}

// Translate UPDATE list, applying relevant type casting and IMPLICIT DEFAULT values.
$update_list = $this->translate_update_list( $update_target_table, $node );
$update_list = $this->translate_update_list( $update_target_table, $node, $update_target );

// Translate WHERE, ORDER BY, and LIMIT clauses.
if ( $where_subquery ) {
Expand Down Expand Up @@ -6275,11 +6275,19 @@ function ( $column ) use ( $is_strict_mode, $insert_map ) {
* For more information about IMPLICIT DEFAULT values in MySQL, see:
* https://dev.mysql.com/doc/refman/8.4/en/data-type-defaults.html#data-type-defaults-implicit
*
* Additionally, this method emulates "ON UPDATE CURRENT_TIMESTAMP" columns.
* In MySQL, such a column is set to the current timestamp when any other
* column in the row changes, unless the statement assigns it explicitly.
*
* For more information about ON UPDATE CURRENT_TIMESTAMP in MySQL, see:
* https://dev.mysql.com/doc/refman/8.4/en/timestamp-initialization.html
*
* @param string $table_name The name of the target table.
* @param WP_Parser_Node $parent_node The "updateList" AST node parent node.
* @param string|null $table_alias Optional. The target table alias. Defaults to the table name.
* @return string The translated UPDATE list.
*/
private function translate_update_list( string $table_name, WP_Parser_Node $parent_node ): string {
private function translate_update_list( string $table_name, WP_Parser_Node $parent_node, ?string $table_alias = null ): string {
$node = $parent_node->get_first_child_node( 'updateList' );

// This method is always used with the main database.
Expand All @@ -6296,7 +6304,7 @@ private function translate_update_list( string $table_name, WP_Parser_Node $pare
$columns_table = $this->information_schema_builder->get_table_name( $is_temporary, 'columns' );
$columns = $this->execute_sqlite_query(
'
SELECT LOWER(column_name) AS COLUMN_NAME, is_nullable, data_type, column_default
SELECT LOWER(column_name) AS COLUMN_NAME, is_nullable, data_type, column_default, extra
FROM ' . $this->quote_sqlite_identifier( $columns_table ) . '
WHERE table_schema = ?
AND table_name = ?
Expand All @@ -6312,7 +6320,8 @@ private function translate_update_list( string $table_name, WP_Parser_Node $pare
$column_map = array_combine( array_column( $columns, 'COLUMN_NAME' ), $columns );

// Translate the UPDATE list, emulating IMPLICIT DEFAULTs for NULL values.
$fragment = '';
$fragment = '';
$assigned_values = array();
foreach ( $node->get_child_nodes() as $i => $update_element ) {
$column_ref = $update_element->get_first_child_node( 'columnRef' );
$column_ref_parts = $column_ref->get_descendant_nodes( 'identifier' );
Expand Down Expand Up @@ -6364,8 +6373,80 @@ private function translate_update_list( string $table_name, WP_Parser_Node $pare
$fragment .= $this->translate( end( $column_ref_parts ) );
$fragment .= ' = ';
$fragment .= $value;

$assigned_values[ strtolower( $column_name ) ] = $value;
}
return $fragment;

// Collect unassigned ON UPDATE CURRENT_TIMESTAMP columns for automatic updates.
$on_update_columns = array();
foreach ( $column_map as $column_name => $column_info ) {
if (
isset( $assigned_values[ $column_name ] )
|| ! str_contains( $column_info['EXTRA'], 'on update CURRENT_TIMESTAMP' )
) {
continue;
}

$on_update_columns[] = $this->quote_sqlite_identifier( $column_name );
}
if ( 0 === count( $on_update_columns ) ) {
return $fragment;
}

/*
* Emulate ON UPDATE CURRENT_TIMESTAMP for columns that are not assigned.
*
* Evaluate assigned expressions once per row and reuse their values to
* detect changes and determine whether to use the current timestamp.
*
* With "updated_at ... ON UPDATE CURRENT_TIMESTAMP", this MySQL query:
*
* UPDATE items SET score = FLOOR(RAND(1) * 10);
*
* Becomes the following SQLite query (simplified):
*
* UPDATE items SET (score, updated_at) = (
* SELECT
* score,
* CASE WHEN items.score IS NOT score THEN CURRENT_TIMESTAMP ELSE items.updated_at END
* FROM (SELECT FLOOR(RAND(1) * 10) AS score)
* );
*
* Here, items.score is the stored value and score is the new value.
* The inner SELECT has no FROM clause, so SQLite cannot flatten it
* and repeat the assigned expressions when checking for changes.
* See: https://www.sqlite.org/optoverview.html#flattening
*/
$quoted_table = $this->quote_sqlite_identifier( $table_alias ?? $table_name );
$assigned_columns = array();
$value_expressions = array();
$changes = array();
foreach ( $assigned_values as $column_name => $value ) {

@adamziel adamziel Oct 23, 2026

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any chance $assigned_values is empty or contains something that isn't a literal column name?

@adamziel adamziel Oct 23, 2026

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Hm, it doesn't seem so. I'll go ahead and merge. Let's rollback and keep the discussion going if I'm wrong here.

$quoted_column = $this->quote_sqlite_identifier( $column_name );
$assigned_columns[] = $quoted_column;
$value_expressions[] = sprintf( '(%s) COLLATE BINARY AS %s', $value, $quoted_column );

// Compare row data using binary collation, qualifying the old values.
$changes[] = sprintf( '%s.%s IS NOT %s COLLATE BINARY', $quoted_table, $quoted_column, $quoted_column );
}
$is_row_changed = implode( ' OR ', $changes );
$row_values = $assigned_columns;
foreach ( $on_update_columns as $quoted_column ) {
$assigned_columns[] = $quoted_column;
$row_values[] = sprintf(
'CASE WHEN %s THEN CURRENT_TIMESTAMP ELSE %s.%s END',
$is_row_changed,
$quoted_table,
$quoted_column
);
}

return sprintf(
'(%s) = (SELECT %s FROM (SELECT %s))',
implode( ', ', $assigned_columns ),
implode( ', ', $row_values ),
implode( ', ', $value_expressions )
);
}

/**
Expand Down Expand Up @@ -7159,7 +7240,6 @@ private function get_sqlite_create_table_statement(

// 6. Generate CREATE TABLE statement columns.
$rows = array();
$on_update_queries = array();
$has_autoincrement = false;
foreach ( $column_info as $column ) {
$query = ' ';
Expand Down Expand Up @@ -7230,13 +7310,6 @@ private function get_sqlite_create_table_statement(
}
}
$rows[] = $query;

if ( 'on update CURRENT_TIMESTAMP' === $column['EXTRA'] ) {
$on_update_queries[] = $this->get_column_on_update_trigger_query(
$table_name,
$column['COLUMN_NAME']
);
}
}

// 6. Generate CREATE TABLE statement constraints, collect indexes.
Expand Down Expand Up @@ -7372,7 +7445,7 @@ function ( $column ) {
$create_table_query .= ' STRICT';
}

return array_merge( array( $create_table_query ), $create_index_queries, $on_update_queries );
return array_merge( array( $create_table_query ), $create_index_queries );
}

/**
Expand Down Expand Up @@ -7705,36 +7778,6 @@ private function get_internal_savepoint_name( string $name ): string {
return sprintf( '%ssavepoint_%s', self::RESERVED_PREFIX, $name );
}

/**
* Get an SQLite query to emulate MySQL "ON UPDATE CURRENT_TIMESTAMP".
*
* In SQLite, "ON UPDATE CURRENT_TIMESTAMP" is not supported. We need to
* create a trigger to emulate this behavior.
*
* @param string $table The table name.
* @param string $column The column name.
*/
private function get_column_on_update_trigger_query( string $table, string $column ): string {
// The trigger wouldn't work for virtual and "WITHOUT ROWID" tables,
// but currently that can't happen as we're not creating such tables.
// See: https://www.sqlite.org/rowidtable.html
$trigger_name = self::RESERVED_PREFIX . "{$table}_{$column}_on_update";
return sprintf(
'
CREATE TRIGGER %s
AFTER UPDATE ON %s
FOR EACH ROW
BEGIN
UPDATE %s SET %s = CURRENT_TIMESTAMP WHERE rowid = NEW.rowid;
END
',
$this->quote_sqlite_identifier( $trigger_name ),
$this->quote_sqlite_identifier( $table ),
$this->quote_sqlite_identifier( $table ),
$this->quote_sqlite_identifier( $column )
);
}

/**
* Format a column default value as a literal for an SQLite CREATE TABLE statement.
*
Expand Down
53 changes: 52 additions & 1 deletion packages/mysql-on-sqlite/src/sqlite/class-wp-sqlite-configurator.php
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Original file line number Diff line number Diff line change
Expand Up @@ -334,13 +334,64 @@ private function save_current_driver_version(): void {
* @param string $saved_version The driver version that last configured the database.
*/
private function run_migrations( string $saved_version ): void {
// Drop ON UPDATE CURRENT_TIMESTAMP triggers created by versions <= 3.1.1.
// Run this before other migrations would drop them by table rebuilds.
if ( version_compare( $saved_version, '3.1.1', '<=' ) ) {
$this->migrate_on_update_triggers();
}

// Fix temporal precision and zero defaults stored by versions <= 3.1.1.
if ( version_compare( $saved_version, '3.1.1', '<=' ) ) {
$this->migrate_datetime_precision();
$this->migrate_temporal_zero_defaults();
}
}

/**
* Migrate ON UPDATE CURRENT_TIMESTAMP triggers to column metadata.
*
* Handles old ON UPDATE triggers with the following name formats:
*
* 1. Versions 3.0.0 to 3.1.1: "_wp_sqlite_{table}_{column}_on_update"
* 2. Versions before 3.0.0: "__{table}_{column}_on_update__"
*/
private function migrate_on_update_triggers(): void {
$connection = $this->driver->get_connection();
$columns_table = $connection->quote_identifier( $this->schema_builder->get_table_name( false, 'columns' ) );
$columns = $this->driver->execute_sqlite_query(
sprintf(
"SELECT c.TABLE_NAME, c.COLUMN_NAME, c.EXTRA, t.name AS TRIGGER_NAME
FROM %s AS c
JOIN main.sqlite_master AS t ON t.type = 'trigger'
AND t.tbl_name = c.TABLE_NAME COLLATE NOCASE
AND (
t.name = '__' || c.TABLE_NAME || '_' || c.COLUMN_NAME || '_on_update__' COLLATE NOCASE
OR t.name = ? || c.TABLE_NAME || '_' || c.COLUMN_NAME || '_on_update' COLLATE NOCASE
)
WHERE c.TABLE_SCHEMA = ?",
$columns_table
),
array( WP_MySQL_On_SQLite::RESERVED_PREFIX, WP_SQLite_Information_Schema_Builder::SAVED_DATABASE_NAME )
)->fetchAll( PDO::FETCH_ASSOC );

foreach ( $columns as $column ) {
if ( ! str_contains( $column['EXTRA'], 'on update CURRENT_TIMESTAMP' ) ) {
$this->driver->execute_sqlite_query(
sprintf( 'UPDATE %s SET EXTRA = ? WHERE TABLE_SCHEMA = ? AND TABLE_NAME = ? AND COLUMN_NAME = ?', $columns_table ),
array(
trim( $column['EXTRA'] . ' on update CURRENT_TIMESTAMP' ),
WP_SQLite_Information_Schema_Builder::SAVED_DATABASE_NAME,
$column['TABLE_NAME'],
$column['COLUMN_NAME'],
)
);
}
$this->driver->execute_sqlite_query(
sprintf( 'DROP TRIGGER main.%s', $connection->quote_identifier( $column['TRIGGER_NAME'] ) )
);
}
}

/**
* Migrate DATETIME_PRECISION values stored by older driver versions.
*
Expand Down Expand Up @@ -422,7 +473,7 @@ private function migrate_temporal_zero_defaults(): void {
}

foreach ( $table_columns as $table_name => $repaired_columns ) {
// Disable driver triggers during row repair. The table rebuild restores them.
// Drop triggers, so they don't run during row repair. The table rebuild drops them anyway.
$triggers = $this->driver->execute_sqlite_query(
"SELECT name FROM sqlite_master WHERE type = 'trigger' AND tbl_name = ? COLLATE NOCASE",
array( $table_name )
Expand Down
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