summaryrefslogtreecommitdiff
path: root/kolab.org/www/drupal-7.26/includes/database/pgsql/schema.inc
diff options
context:
space:
mode:
Diffstat (limited to 'kolab.org/www/drupal-7.26/includes/database/pgsql/schema.inc')
-rw-r--r--kolab.org/www/drupal-7.26/includes/database/pgsql/schema.inc617
1 files changed, 617 insertions, 0 deletions
diff --git a/kolab.org/www/drupal-7.26/includes/database/pgsql/schema.inc b/kolab.org/www/drupal-7.26/includes/database/pgsql/schema.inc
new file mode 100644
index 0000000..49adbf9
--- /dev/null
+++ b/kolab.org/www/drupal-7.26/includes/database/pgsql/schema.inc
@@ -0,0 +1,617 @@
+<?php
+
+/**
+ * @file
+ * Database schema code for PostgreSQL database servers.
+ */
+
+/**
+ * @ingroup schemaapi
+ * @{
+ */
+
+class DatabaseSchema_pgsql extends DatabaseSchema {
+
+ /**
+ * A cache of information about blob columns and sequences of tables.
+ *
+ * This is collected by DatabaseConnection_pgsql->queryTableInformation(),
+ * by introspecting the database.
+ *
+ * @see DatabaseConnection_pgsql->queryTableInformation()
+ * @var array
+ */
+ protected $tableInformation = array();
+
+ /**
+ * Fetch the list of blobs and sequences used on a table.
+ *
+ * We introspect the database to collect the information required by insert
+ * and update queries.
+ *
+ * @param $table_name
+ * The non-prefixed name of the table.
+ * @return
+ * An object with two member variables:
+ * - 'blob_fields' that lists all the blob fields in the table.
+ * - 'sequences' that lists the sequences used in that table.
+ */
+ public function queryTableInformation($table) {
+ // Generate a key to reference this table's information on.
+ $key = $this->connection->prefixTables('{' . $table . '}');
+ if (!strpos($key, '.')) {
+ $key = 'public.' . $key;
+ }
+
+ if (!isset($this->tableInformation[$key])) {
+ // Split the key into schema and table for querying.
+ list($schema, $table_name) = explode('.', $key);
+ $table_information = (object) array(
+ 'blob_fields' => array(),
+ 'sequences' => array(),
+ );
+ // Don't use {} around information_schema.columns table.
+ $result = $this->connection->query("SELECT column_name, data_type, column_default FROM information_schema.columns WHERE table_schema = :schema AND table_name = :table AND (data_type = 'bytea' OR (numeric_precision IS NOT NULL AND column_default LIKE :default))", array(
+ ':schema' => $schema,
+ ':table' => $table_name,
+ ':default' => '%nextval%',
+ ));
+ foreach ($result as $column) {
+ if ($column->data_type == 'bytea') {
+ $table_information->blob_fields[$column->column_name] = TRUE;
+ }
+ elseif (preg_match("/nextval\('([^']+)'/", $column->column_default, $matches)) {
+ // We must know of any sequences in the table structure to help us
+ // return the last insert id. If there is more than 1 sequences the
+ // first one (index 0 of the sequences array) will be used.
+ $table_information->sequences[] = $matches[1];
+ $table_information->serial_fields[] = $column->column_name;
+ }
+ }
+ $this->tableInformation[$key] = $table_information;
+ }
+ return $this->tableInformation[$key];
+ }
+
+ /**
+ * Fetch the list of CHECK constraints used on a field.
+ *
+ * We introspect the database to collect the information required by field
+ * alteration.
+ *
+ * @param $table
+ * The non-prefixed name of the table.
+ * @param $field
+ * The name of the field.
+ * @return
+ * An array of all the checks for the field.
+ */
+ public function queryFieldInformation($table, $field) {
+ $prefixInfo = $this->getPrefixInfo($table, TRUE);
+
+ // Split the key into schema and table for querying.
+ $schema = $prefixInfo['schema'];
+ $table_name = $prefixInfo['table'];
+
+ $field_information = (object) array(
+ 'checks' => array(),
+ );
+ $checks = $this->connection->query("SELECT conname FROM pg_class cl INNER JOIN pg_constraint co ON co.conrelid = cl.oid INNER JOIN pg_attribute attr ON attr.attrelid = cl.oid AND attr.attnum = ANY (co.conkey) INNER JOIN pg_namespace ns ON cl.relnamespace = ns.oid WHERE co.contype = 'c' AND ns.nspname = :schema AND cl.relname = :table AND attr.attname = :column", array(
+ ':schema' => $schema,
+ ':table' => $table_name,
+ ':column' => $field,
+ ));
+ $field_information = $checks->fetchCol();
+
+ return $field_information;
+ }
+
+ /**
+ * Generate SQL to create a new table from a Drupal schema definition.
+ *
+ * @param $name
+ * The name of the table to create.
+ * @param $table
+ * A Schema API table definition array.
+ * @return
+ * An array of SQL statements to create the table.
+ */
+ protected function createTableSql($name, $table) {
+ $sql_fields = array();
+ foreach ($table['fields'] as $field_name => $field) {
+ $sql_fields[] = $this->createFieldSql($field_name, $this->processField($field));
+ }
+
+ $sql_keys = array();
+ if (isset($table['primary key']) && is_array($table['primary key'])) {
+ $sql_keys[] = 'PRIMARY KEY (' . implode(', ', $table['primary key']) . ')';
+ }
+ if (isset($table['unique keys']) && is_array($table['unique keys'])) {
+ foreach ($table['unique keys'] as $key_name => $key) {
+ $sql_keys[] = 'CONSTRAINT ' . $this->prefixNonTable($name, $key_name, 'key') . ' UNIQUE (' . implode(', ', $key) . ')';
+ }
+ }
+
+ $sql = "CREATE TABLE {" . $name . "} (\n\t";
+ $sql .= implode(",\n\t", $sql_fields);
+ if (count($sql_keys) > 0) {
+ $sql .= ",\n\t";
+ }
+ $sql .= implode(",\n\t", $sql_keys);
+ $sql .= "\n)";
+ $statements[] = $sql;
+
+ if (isset($table['indexes']) && is_array($table['indexes'])) {
+ foreach ($table['indexes'] as $key_name => $key) {
+ $statements[] = $this->_createIndexSql($name, $key_name, $key);
+ }
+ }
+
+ // Add table comment.
+ if (!empty($table['description'])) {
+ $statements[] = 'COMMENT ON TABLE {' . $name . '} IS ' . $this->prepareComment($table['description']);
+ }
+
+ // Add column comments.
+ foreach ($table['fields'] as $field_name => $field) {
+ if (!empty($field['description'])) {
+ $statements[] = 'COMMENT ON COLUMN {' . $name . '}.' . $field_name . ' IS ' . $this->prepareComment($field['description']);
+ }
+ }
+
+ return $statements;
+ }
+
+ /**
+ * Create an SQL string for a field to be used in table creation or
+ * alteration.
+ *
+ * Before passing a field out of a schema definition into this
+ * function it has to be processed by _db_process_field().
+ *
+ * @param $name
+ * Name of the field.
+ * @param $spec
+ * The field specification, as per the schema data structure format.
+ */
+ protected function createFieldSql($name, $spec) {
+ $sql = $name . ' ' . $spec['pgsql_type'];
+
+ if (isset($spec['type']) && $spec['type'] == 'serial') {
+ unset($spec['not null']);
+ }
+
+ if (in_array($spec['pgsql_type'], array('varchar', 'character', 'text')) && isset($spec['length'])) {
+ $sql .= '(' . $spec['length'] . ')';
+ }
+ elseif (isset($spec['precision']) && isset($spec['scale'])) {
+ $sql .= '(' . $spec['precision'] . ', ' . $spec['scale'] . ')';
+ }
+
+ if (!empty($spec['unsigned'])) {
+ $sql .= " CHECK ($name >= 0)";
+ }
+
+ if (isset($spec['not null'])) {
+ if ($spec['not null']) {
+ $sql .= ' NOT NULL';
+ }
+ else {
+ $sql .= ' NULL';
+ }
+ }
+ if (isset($spec['default'])) {
+ $default = is_string($spec['default']) ? "'" . $spec['default'] . "'" : $spec['default'];
+ $sql .= " default $default";
+ }
+
+ return $sql;
+ }
+
+ /**
+ * Set database-engine specific properties for a field.
+ *
+ * @param $field
+ * A field description array, as specified in the schema documentation.
+ */
+ protected function processField($field) {
+ if (!isset($field['size'])) {
+ $field['size'] = 'normal';
+ }
+
+ // Set the correct database-engine specific datatype.
+ // In case one is already provided, force it to lowercase.
+ if (isset($field['pgsql_type'])) {
+ $field['pgsql_type'] = drupal_strtolower($field['pgsql_type']);
+ }
+ else {
+ $map = $this->getFieldTypeMap();
+ $field['pgsql_type'] = $map[$field['type'] . ':' . $field['size']];
+ }
+
+ if (!empty($field['unsigned'])) {
+ // Unsigned datatypes are not supported in PostgreSQL 8.3. In MySQL,
+ // they are used to ensure a positive number is inserted and it also
+ // doubles the maximum integer size that can be stored in a field.
+ // The PostgreSQL schema in Drupal creates a check constraint
+ // to ensure that a value inserted is >= 0. To provide the extra
+ // integer capacity, here, we bump up the column field size.
+ if (!isset($map)) {
+ $map = $this->getFieldTypeMap();
+ }
+ switch ($field['pgsql_type']) {
+ case 'smallint':
+ $field['pgsql_type'] = $map['int:medium'];
+ break;
+ case 'int' :
+ $field['pgsql_type'] = $map['int:big'];
+ break;
+ }
+ }
+ if (isset($field['type']) && $field['type'] == 'serial') {
+ unset($field['not null']);
+ }
+ return $field;
+ }
+
+ /**
+ * This maps a generic data type in combination with its data size
+ * to the engine-specific data type.
+ */
+ function getFieldTypeMap() {
+ // Put :normal last so it gets preserved by array_flip. This makes
+ // it much easier for modules (such as schema.module) to map
+ // database types back into schema types.
+ // $map does not use drupal_static as its value never changes.
+ static $map = array(
+ 'varchar:normal' => 'varchar',
+ 'char:normal' => 'character',
+
+ 'text:tiny' => 'text',
+ 'text:small' => 'text',
+ 'text:medium' => 'text',
+ 'text:big' => 'text',
+ 'text:normal' => 'text',
+
+ 'int:tiny' => 'smallint',
+ 'int:small' => 'smallint',
+ 'int:medium' => 'int',
+ 'int:big' => 'bigint',
+ 'int:normal' => 'int',
+
+ 'float:tiny' => 'real',
+ 'float:small' => 'real',
+ 'float:medium' => 'real',
+ 'float:big' => 'double precision',
+ 'float:normal' => 'real',
+
+ 'numeric:normal' => 'numeric',
+
+ 'blob:big' => 'bytea',
+ 'blob:normal' => 'bytea',
+
+ 'serial:tiny' => 'serial',
+ 'serial:small' => 'serial',
+ 'serial:medium' => 'serial',
+ 'serial:big' => 'bigserial',
+ 'serial:normal' => 'serial',
+ );
+ return $map;
+ }
+
+ protected function _createKeySql($fields) {
+ $return = array();
+ foreach ($fields as $field) {
+ if (is_array($field)) {
+ $return[] = 'substr(' . $field[0] . ', 1, ' . $field[1] . ')';
+ }
+ else {
+ $return[] = '"' . $field . '"';
+ }
+ }
+ return implode(', ', $return);
+ }
+
+ function renameTable($table, $new_name) {
+ if (!$this->tableExists($table)) {
+ throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot rename %table to %table_new: table %table doesn't exist.", array('%table' => $table, '%table_new' => $new_name)));
+ }
+ if ($this->tableExists($new_name)) {
+ throw new DatabaseSchemaObjectExistsException(t("Cannot rename %table to %table_new: table %table_new already exists.", array('%table' => $table, '%table_new' => $new_name)));
+ }
+
+ // Get the schema and tablename for the old table.
+ $old_full_name = $this->connection->prefixTables('{' . $table . '}');
+ list($old_schema, $old_table_name) = strpos($old_full_name, '.') ? explode('.', $old_full_name) : array('public', $old_full_name);
+
+ // Index names and constraint names are global in PostgreSQL, so we need to
+ // rename them when renaming the table.
+ $indexes = $this->connection->query('SELECT indexname FROM pg_indexes WHERE schemaname = :schema AND tablename = :table', array(':schema' => $old_schema, ':table' => $old_table_name));
+ foreach ($indexes as $index) {
+ if (preg_match('/^' . preg_quote($old_full_name) . '_(.*)$/', $index->indexname, $matches)) {
+ $index_name = $matches[1];
+ $this->connection->query('ALTER INDEX ' . $index->indexname . ' RENAME TO {' . $new_name . '}_' . $index_name);
+ }
+ }
+
+ // Now rename the table.
+ // Ensure the new table name does not include schema syntax.
+ $prefixInfo = $this->getPrefixInfo($new_name);
+ $this->connection->query('ALTER TABLE {' . $table . '} RENAME TO ' . $prefixInfo['table']);
+ }
+
+ public function dropTable($table) {
+ if (!$this->tableExists($table)) {
+ return FALSE;
+ }
+
+ $this->connection->query('DROP TABLE {' . $table . '}');
+ return TRUE;
+ }
+
+ public function addField($table, $field, $spec, $new_keys = array()) {
+ if (!$this->tableExists($table)) {
+ throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add field %table.%field: table doesn't exist.", array('%field' => $field, '%table' => $table)));
+ }
+ if ($this->fieldExists($table, $field)) {
+ throw new DatabaseSchemaObjectExistsException(t("Cannot add field %table.%field: field already exists.", array('%field' => $field, '%table' => $table)));
+ }
+
+ $fixnull = FALSE;
+ if (!empty($spec['not null']) && !isset($spec['default'])) {
+ $fixnull = TRUE;
+ $spec['not null'] = FALSE;
+ }
+ $query = 'ALTER TABLE {' . $table . '} ADD COLUMN ';
+ $query .= $this->createFieldSql($field, $this->processField($spec));
+ $this->connection->query($query);
+ if (isset($spec['initial'])) {
+ $this->connection->update($table)
+ ->fields(array($field => $spec['initial']))
+ ->execute();
+ }
+ if ($fixnull) {
+ $this->connection->query("ALTER TABLE {" . $table . "} ALTER $field SET NOT NULL");
+ }
+ if (isset($new_keys)) {
+ $this->_createKeys($table, $new_keys);
+ }
+ // Add column comment.
+ if (!empty($spec['description'])) {
+ $this->connection->query('COMMENT ON COLUMN {' . $table . '}.' . $field . ' IS ' . $this->prepareComment($spec['description']));
+ }
+ }
+
+ public function dropField($table, $field) {
+ if (!$this->fieldExists($table, $field)) {
+ return FALSE;
+ }
+
+ $this->connection->query('ALTER TABLE {' . $table . '} DROP COLUMN "' . $field . '"');
+ return TRUE;
+ }
+
+ public function fieldSetDefault($table, $field, $default) {
+ if (!$this->fieldExists($table, $field)) {
+ throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot set default value of field %table.%field: field doesn't exist.", array('%table' => $table, '%field' => $field)));
+ }
+
+ if (!isset($default)) {
+ $default = 'NULL';
+ }
+ else {
+ $default = is_string($default) ? "'$default'" : $default;
+ }
+
+ $this->connection->query('ALTER TABLE {' . $table . '} ALTER COLUMN "' . $field . '" SET DEFAULT ' . $default);
+ }
+
+ public function fieldSetNoDefault($table, $field) {
+ if (!$this->fieldExists($table, $field)) {
+ throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot remove default value of field %table.%field: field doesn't exist.", array('%table' => $table, '%field' => $field)));
+ }
+
+ $this->connection->query('ALTER TABLE {' . $table . '} ALTER COLUMN "' . $field . '" DROP DEFAULT');
+ }
+
+ public function indexExists($table, $name) {
+ // Details http://www.postgresql.org/docs/8.3/interactive/view-pg-indexes.html
+ $index_name = '{' . $table . '}_' . $name . '_idx';
+ return (bool) $this->connection->query("SELECT 1 FROM pg_indexes WHERE indexname = '$index_name'")->fetchField();
+ }
+
+ /**
+ * Helper function: check if a constraint (PK, FK, UK) exists.
+ *
+ * @param $table
+ * The name of the table.
+ * @param $name
+ * The name of the constraint (typically 'pkey' or '[constraint]_key').
+ */
+ protected function constraintExists($table, $name) {
+ $constraint_name = '{' . $table . '}_' . $name;
+ return (bool) $this->connection->query("SELECT 1 FROM pg_constraint WHERE conname = '$constraint_name'")->fetchField();
+ }
+
+ public function addPrimaryKey($table, $fields) {
+ if (!$this->tableExists($table)) {
+ throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add primary key to table %table: table doesn't exist.", array('%table' => $table)));
+ }
+ if ($this->constraintExists($table, 'pkey')) {
+ throw new DatabaseSchemaObjectExistsException(t("Cannot add primary key to table %table: primary key already exists.", array('%table' => $table)));
+ }
+
+ $this->connection->query('ALTER TABLE {' . $table . '} ADD PRIMARY KEY (' . implode(',', $fields) . ')');
+ }
+
+ public function dropPrimaryKey($table) {
+ if (!$this->constraintExists($table, 'pkey')) {
+ return FALSE;
+ }
+
+ $this->connection->query('ALTER TABLE {' . $table . '} DROP CONSTRAINT ' . $this->prefixNonTable($table, 'pkey'));
+ return TRUE;
+ }
+
+ function addUniqueKey($table, $name, $fields) {
+ if (!$this->tableExists($table)) {
+ throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add unique key %name to table %table: table doesn't exist.", array('%table' => $table, '%name' => $name)));
+ }
+ if ($this->constraintExists($table, $name . '_key')) {
+ throw new DatabaseSchemaObjectExistsException(t("Cannot add unique key %name to table %table: unique key already exists.", array('%table' => $table, '%name' => $name)));
+ }
+
+ $this->connection->query('ALTER TABLE {' . $table . '} ADD CONSTRAINT "' . $this->prefixNonTable($table, $name, 'key') . '" UNIQUE (' . implode(',', $fields) . ')');
+ }
+
+ public function dropUniqueKey($table, $name) {
+ if (!$this->constraintExists($table, $name . '_key')) {
+ return FALSE;
+ }
+
+ $this->connection->query('ALTER TABLE {' . $table . '} DROP CONSTRAINT "' . $this->prefixNonTable($table, $name, 'key') . '"');
+ return TRUE;
+ }
+
+ public function addIndex($table, $name, $fields) {
+ if (!$this->tableExists($table)) {
+ throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add index %name to table %table: table doesn't exist.", array('%table' => $table, '%name' => $name)));
+ }
+ if ($this->indexExists($table, $name)) {
+ throw new DatabaseSchemaObjectExistsException(t("Cannot add index %name to table %table: index already exists.", array('%table' => $table, '%name' => $name)));
+ }
+
+ $this->connection->query($this->_createIndexSql($table, $name, $fields));
+ }
+
+ public function dropIndex($table, $name) {
+ if (!$this->indexExists($table, $name)) {
+ return FALSE;
+ }
+
+ $this->connection->query('DROP INDEX ' . $this->prefixNonTable($table, $name, 'idx'));
+ return TRUE;
+ }
+
+ public function changeField($table, $field, $field_new, $spec, $new_keys = array()) {
+ if (!$this->fieldExists($table, $field)) {
+ throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot change the definition of field %table.%name: field doesn't exist.", array('%table' => $table, '%name' => $field)));
+ }
+ if (($field != $field_new) && $this->fieldExists($table, $field_new)) {
+ throw new DatabaseSchemaObjectExistsException(t("Cannot rename field %table.%name to %name_new: target field already exists.", array('%table' => $table, '%name' => $field, '%name_new' => $field_new)));
+ }
+
+ $spec = $this->processField($spec);
+
+ // We need to typecast the new column to best be able to transfer the data
+ // Schema_pgsql::getFieldTypeMap() will return possibilities that are not
+ // 'cast-able' such as 'serial' - so they need to be casted int instead.
+ if (in_array($spec['pgsql_type'], array('serial', 'bigserial', 'numeric'))) {
+ $typecast = 'int';
+ }
+ else {
+ $typecast = $spec['pgsql_type'];
+ }
+
+ if (in_array($spec['pgsql_type'], array('varchar', 'character', 'text')) && isset($spec['length'])) {
+ $typecast .= '(' . $spec['length'] . ')';
+ }
+ elseif (isset($spec['precision']) && isset($spec['scale'])) {
+ $typecast .= '(' . $spec['precision'] . ', ' . $spec['scale'] . ')';
+ }
+
+ // Remove old check constraints.
+ $field_info = $this->queryFieldInformation($table, $field);
+
+ foreach ($field_info as $check) {
+ $this->connection->query('ALTER TABLE {' . $table . '} DROP CONSTRAINT "' . $check . '"');
+ }
+
+ // Remove old default.
+ $this->fieldSetNoDefault($table, $field);
+
+ $this->connection->query('ALTER TABLE {' . $table . '} ALTER "' . $field . '" TYPE ' . $typecast . ' USING "' . $field . '"::' . $typecast);
+
+ if (isset($spec['not null'])) {
+ if ($spec['not null']) {
+ $nullaction = 'SET NOT NULL';
+ }
+ else {
+ $nullaction = 'DROP NOT NULL';
+ }
+ $this->connection->query('ALTER TABLE {' . $table . '} ALTER "' . $field . '" ' . $nullaction);
+ }
+
+ if (in_array($spec['pgsql_type'], array('serial', 'bigserial'))) {
+ // Type "serial" is known to PostgreSQL, but *only* during table creation,
+ // not when altering. Because of that, the sequence needs to be created
+ // and initialized by hand.
+ $seq = "{" . $table . "}_" . $field_new . "_seq";
+ $this->connection->query("CREATE SEQUENCE " . $seq);
+ // Set sequence to maximal field value to not conflict with existing
+ // entries.
+ $this->connection->query("SELECT setval('" . $seq . "', MAX(\"" . $field . '")) FROM {' . $table . "}");
+ $this->connection->query('ALTER TABLE {' . $table . '} ALTER "' . $field . '" SET DEFAULT nextval(\'' . $seq . '\')');
+ }
+
+ // Rename the column if necessary.
+ if ($field != $field_new) {
+ $this->connection->query('ALTER TABLE {' . $table . '} RENAME "' . $field . '" TO "' . $field_new . '"');
+ }
+
+ // Add unsigned check if necessary.
+ if (!empty($spec['unsigned'])) {
+ $this->connection->query('ALTER TABLE {' . $table . '} ADD CHECK ("' . $field_new . '" >= 0)');
+ }
+
+ // Add default if necessary.
+ if (isset($spec['default'])) {
+ $this->fieldSetDefault($table, $field_new, $spec['default']);
+ }
+
+ // Change description if necessary.
+ if (!empty($spec['description'])) {
+ $this->connection->query('COMMENT ON COLUMN {' . $table . '}."' . $field_new . '" IS ' . $this->prepareComment($spec['description']));
+ }
+
+ if (isset($new_keys)) {
+ $this->_createKeys($table, $new_keys);
+ }
+ }
+
+ protected function _createIndexSql($table, $name, $fields) {
+ $query = 'CREATE INDEX "' . $this->prefixNonTable($table, $name, 'idx') . '" ON {' . $table . '} (';
+ $query .= $this->_createKeySql($fields) . ')';
+ return $query;
+ }
+
+ protected function _createKeys($table, $new_keys) {
+ if (isset($new_keys['primary key'])) {
+ $this->addPrimaryKey($table, $new_keys['primary key']);
+ }
+ if (isset($new_keys['unique keys'])) {
+ foreach ($new_keys['unique keys'] as $name => $fields) {
+ $this->addUniqueKey($table, $name, $fields);
+ }
+ }
+ if (isset($new_keys['indexes'])) {
+ foreach ($new_keys['indexes'] as $name => $fields) {
+ $this->addIndex($table, $name, $fields);
+ }
+ }
+ }
+
+ /**
+ * Retrieve a table or column comment.
+ */
+ public function getComment($table, $column = NULL) {
+ $info = $this->getPrefixInfo($table);
+ // Don't use {} around pg_class, pg_attribute tables.
+ if (isset($column)) {
+ return $this->connection->query('SELECT col_description(oid, attnum) FROM pg_class, pg_attribute WHERE attrelid = oid AND relname = ? AND attname = ?', array($info['table'], $column))->fetchField();
+ }
+ else {
+ return $this->connection->query('SELECT obj_description(oid, ?) FROM pg_class WHERE relname = ?', array('pg_class', $info['table']))->fetchField();
+ }
+ }
+}