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MDL-34145 postgres driver: fix get_tables perf on <= 9.0

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The query of the information_schema view seems to be painfully slow on
older versions of postgres (2000ms instead of 20ms). Therefore, it is
worth detecting that case, and using a more postgres specific feedback.
This is particularly important for 2.3+ unit tests.

Thanks to Petr Skoda for his help with this.
This commit is contained in:
Tim Hunt
2012-07-02 16:24:10 +01:00
parent ec7a8c38d9
commit 3aa0f88b6e
1 changed files with 15 additions and 6 deletions
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lib/dml/pgsql_native_moodle_database.php
+15 -6
View File
@@ -278,12 +278,21 @@ class pgsql_native_moodle_database extends moodle_database {
}
$this->tables = array();
$prefix = str_replace('_', '|_', $this->prefix);
// Get them from information_schema instead of catalog as far as
// we want to get only own session temp objects (catalog returns all)
$sql = "SELECT table_name
FROM information_schema.tables
WHERE table_name LIKE '$prefix%' ESCAPE '|'
AND table_type IN ('BASE TABLE', 'LOCAL TEMPORARY')";
if ($this->is_min_version('9.1')) {
// Use ANSI standard information_schema in recent versions where it is fast enough.
$sql = "SELECT table_name
FROM information_schema.tables
WHERE table_name LIKE '$prefix%' ESCAPE '|'
AND table_type IN ('BASE TABLE', 'LOCAL TEMPORARY')";
} else {
// information_schema is horribly slow in <= 9.0, so use pg internals.
// Note the pg_is_other_temp_schema. We only want temp objects from our own session.
$sql = "SELECT c.relname
FROM pg_class c
WHERE c.relname LIKE '$prefix%' ESCAPE '|'
AND c.relkind = 'r'
AND NOT pg_is_other_temp_schema(c.relnamespace)";
}
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);