1 <?php

     2 

     3 /**

     4  * @file

     5  * Database schema code for PostgreSQL database servers.

     6  */

     7 

     8 /**

     9  * @ingroup schemaapi

    10  * @{

    11  */

    12 

    13 class DatabaseSchema_pgsql extends DatabaseSchema {

    14 

    15   /**

    16    * A cache of information about blob columns and sequences of tables.

    17    *

    18    * This is collected by DatabaseConnection_pgsql->queryTableInformation(),

    19    * by introspecting the database.

    20    *

    21    * @see DatabaseConnection_pgsql->queryTableInformation()

    22    * @var array

    23    */

    24   protected $tableInformation = array();

    25 

    26   /**

    27    * Fetch the list of blobs and sequences used on a table.

    28    *

    29    * We introspect the database to collect the information required by insert

    30    * and update queries.

    31    *

    32    * @param $table_name

    33    *   The non-prefixed name of the table.

    34    * @return

    35    *   An object with two member variables:

    36    *     - 'blob_fields' that lists all the blob fields in the table.

    37    *     - 'sequences' that lists the sequences used in that table.

    38    */

    39   public function queryTableInformation($table) {

    40     // Generate a key to reference this table's information on.

    41     $key = $this->connection->prefixTables('{' . $table . '}');

    42     if (!strpos($key, '.')) {

    43       $key = 'public.' . $key;

    44     }

    45 

    46     if (!isset($this->tableInformation[$key])) {

    47       // Split the key into schema and table for querying.

    48       list($schema, $table_name) = explode('.', $key);

    49       $table_information = (object) array(

    50         'blob_fields' => array(),

    51         'sequences' => array(),

    52       );

    53       // Don't use {} around information_schema.columns table.

    54       $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(

    55         ':schema' => $schema,

    56         ':table' => $table_name,

    57         ':default' => '%nextval%',

    58       ));

    59       foreach ($result as $column) {

    60         if ($column->data_type == 'bytea') {

    61           $table_information->blob_fields[$column->column_name] = TRUE;

    62         }

    63         elseif (preg_match("/nextval\('([^']+)'/", $column->column_default, $matches)) {

    64           // We must know of any sequences in the table structure to help us

    65           // return the last insert id. If there is more than 1 sequences the

    66           // first one (index 0 of the sequences array) will be used.

    67           $table_information->sequences[] = $matches[1];

    68           $table_information->serial_fields[] = $column->column_name;

    69         }

    70       }

    71       $this->tableInformation[$key] = $table_information;

    72     }

    73     return $this->tableInformation[$key];

    74   }

    75 

    76   /**

    77    * Fetch the list of CHECK constraints used on a field.

    78    *

    79    * We introspect the database to collect the information required by field

    80    * alteration.

    81    *

    82    * @param $table

    83    *   The non-prefixed name of the table.

    84    * @param $field

    85    *   The name of the field.

    86    * @return

    87    *   An array of all the checks for the field.

    88    */

    89   public function queryFieldInformation($table, $field) {

    90     $prefixInfo = $this->getPrefixInfo($table, TRUE);

    91 

    92     // Split the key into schema and table for querying.

    93     $schema = $prefixInfo['schema'];

    94     $table_name = $prefixInfo['table'];

    95 

    96     $field_information = (object) array(

    97         'checks' => array(),

    98     );

    99     $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(

   100       ':schema' => $schema,

   101       ':table' => $table_name,

   102       ':column' => $field,

   103     ));

   104     $field_information = $checks->fetchCol();

   105 

   106     return $field_information;

   107   }

   108 

   109   /**

   110    * Generate SQL to create a new table from a Drupal schema definition.

   111    *

   112    * @param $name

   113    *   The name of the table to create.

   114    * @param $table

   115    *   A Schema API table definition array.

   116    * @return

   117    *   An array of SQL statements to create the table.

   118    */

   119   protected function createTableSql($name, $table) {

   120     $sql_fields = array();

   121     foreach ($table['fields'] as $field_name => $field) {

   122       $sql_fields[] = $this->createFieldSql($field_name, $this->processField($field));

   123     }

   124 

   125     $sql_keys = array();

   126     if (isset($table['primary key']) && is_array($table['primary key'])) {

   127       $sql_keys[] = 'PRIMARY KEY (' . implode(', ', $table['primary key']) . ')';

   128     }

   129     if (isset($table['unique keys']) && is_array($table['unique keys'])) {

   130       foreach ($table['unique keys'] as $key_name => $key) {

   131         $sql_keys[] = 'CONSTRAINT ' . $this->prefixNonTable($name, $key_name, 'key') . ' UNIQUE (' . implode(', ', $key) . ')';

   132       }

   133     }

   134 

   135     $sql = "CREATE TABLE {" . $name . "} (\n\t";

   136     $sql .= implode(",\n\t", $sql_fields);

   137     if (count($sql_keys) > 0) {

   138       $sql .= ",\n\t";

   139     }

   140     $sql .= implode(",\n\t", $sql_keys);

   141     $sql .= "\n)";

   142     $statements[] = $sql;

   143 

   144     if (isset($table['indexes']) && is_array($table['indexes'])) {

   145       foreach ($table['indexes'] as $key_name => $key) {

   146         $statements[] = $this->_createIndexSql($name, $key_name, $key);

   147       }

   148     }

   149 

   150     // Add table comment.

   151     if (!empty($table['description'])) {

   152       $statements[] = 'COMMENT ON TABLE {' . $name . '} IS ' . $this->prepareComment($table['description']);

   153     }

   154 

   155     // Add column comments.

   156     foreach ($table['fields'] as $field_name => $field) {

   157       if (!empty($field['description'])) {

   158         $statements[] = 'COMMENT ON COLUMN {' . $name . '}.' . $field_name . ' IS ' . $this->prepareComment($field['description']);

   159       }

   160     }

   161 

   162     return $statements;

   163   }

   164 

   165   /**

   166    * Create an SQL string for a field to be used in table creation or

   167    * alteration.

   168    *

   169    * Before passing a field out of a schema definition into this

   170    * function it has to be processed by _db_process_field().

   171    *

   172    * @param $name

   173    *    Name of the field.

   174    * @param $spec

   175    *    The field specification, as per the schema data structure format.

   176    */

   177   protected function createFieldSql($name, $spec) {

   178     $sql = $name . ' ' . $spec['pgsql_type'];

   179 

   180     if (isset($spec['type']) && $spec['type'] == 'serial') {

   181       unset($spec['not null']);

   182     }

   183 

   184     if (in_array($spec['pgsql_type'], array('varchar', 'character', 'text')) && isset($spec['length'])) {

   185       $sql .= '(' . $spec['length'] . ')';

   186     }

   187     elseif (isset($spec['precision']) && isset($spec['scale'])) {

   188       $sql .= '(' . $spec['precision'] . ', ' . $spec['scale'] . ')';

   189     }

   190 

   191     if (!empty($spec['unsigned'])) {

   192       $sql .= " CHECK ($name >= 0)";

   193     }

   194 

   195     if (isset($spec['not null'])) {

   196       if ($spec['not null']) {

   197         $sql .= ' NOT NULL';

   198       }

   199       else {

   200         $sql .= ' NULL';

   201       }

   202     }

   203     if (isset($spec['default'])) {

   204       $default = is_string($spec['default']) ? "'" . $spec['default'] . "'" : $spec['default'];

   205       $sql .= " default $default";

   206     }

   207 

   208     return $sql;

   209   }

   210 

   211   /**

   212    * Set database-engine specific properties for a field.

   213    *

   214    * @param $field

   215    *   A field description array, as specified in the schema documentation.

   216    */

   217   protected function processField($field) {

   218     if (!isset($field['size'])) {

   219       $field['size'] = 'normal';

   220     }

   221 

   222     // Set the correct database-engine specific datatype.

   223     // In case one is already provided, force it to lowercase.

   224     if (isset($field['pgsql_type'])) {

   225       $field['pgsql_type'] = drupal_strtolower($field['pgsql_type']);

   226     }

   227     else {

   228       $map = $this->getFieldTypeMap();

   229       $field['pgsql_type'] = $map[$field['type'] . ':' . $field['size']];

   230     }

   231 

   232     if (!empty($field['unsigned'])) {

   233       // Unsigned datatypes are not supported in PostgreSQL 8.3. In MySQL,

   234       // they are used to ensure a positive number is inserted and it also

   235       // doubles the maximum integer size that can be stored in a field.

   236       // The PostgreSQL schema in Drupal creates a check constraint

   237       // to ensure that a value inserted is >= 0. To provide the extra

   238       // integer capacity, here, we bump up the column field size.

   239       if (!isset($map)) {

   240         $map = $this->getFieldTypeMap();

   241       }

   242       switch ($field['pgsql_type']) {

   243         case 'smallint':

   244           $field['pgsql_type'] = $map['int:medium'];

   245           break;

   246         case 'int' :

   247           $field['pgsql_type'] = $map['int:big'];

   248           break;

   249       }

   250     }

   251     if (isset($field['type']) && $field['type'] == 'serial') {

   252       unset($field['not null']);

   253     }

   254     return $field;

   255   }

   256 

   257   /**

   258    * This maps a generic data type in combination with its data size

   259    * to the engine-specific data type.

   260    */

   261   function getFieldTypeMap() {

   262     // Put :normal last so it gets preserved by array_flip. This makes

   263     // it much easier for modules (such as schema.module) to map

   264     // database types back into schema types.

   265     // $map does not use drupal_static as its value never changes.

   266     static $map = array(

   267       'varchar:normal' => 'varchar',

   268       'char:normal' => 'character',

   269 

   270       'text:tiny' => 'text',

   271       'text:small' => 'text',

   272       'text:medium' => 'text',

   273       'text:big' => 'text',

   274       'text:normal' => 'text',

   275 

   276       'int:tiny' => 'smallint',

   277       'int:small' => 'smallint',

   278       'int:medium' => 'int',

   279       'int:big' => 'bigint',

   280       'int:normal' => 'int',

   281 

   282       'float:tiny' => 'real',

   283       'float:small' => 'real',

   284       'float:medium' => 'real',

   285       'float:big' => 'double precision',

   286       'float:normal' => 'real',

   287 

   288       'numeric:normal' => 'numeric',

   289 

   290       'blob:big' => 'bytea',

   291       'blob:normal' => 'bytea',

   292 

   293       'serial:tiny' => 'serial',

   294       'serial:small' => 'serial',

   295       'serial:medium' => 'serial',

   296       'serial:big' => 'bigserial',

   297       'serial:normal' => 'serial',

   298       );

   299     return $map;

   300   }

   301 

   302   protected function _createKeySql($fields) {

   303     $return = array();

   304     foreach ($fields as $field) {

   305       if (is_array($field)) {

   306         $return[] = 'substr(' . $field[0] . ', 1, ' . $field[1] . ')';

   307       }

   308       else {

   309         $return[] = '"' . $field . '"';

   310       }

   311     }

   312     return implode(', ', $return);

   313   }

   314 

   315   function renameTable($table, $new_name) {

   316     if (!$this->tableExists($table)) {

   317       throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot rename @table to @table_new: table @table doesn't exist.", array('@table' => $table, '@table_new' => $new_name)));

   318     }

   319     if ($this->tableExists($new_name)) {

   320       throw new DatabaseSchemaObjectExistsException(t("Cannot rename @table to @table_new: table @table_new already exists.", array('@table' => $table, '@table_new' => $new_name)));

   321     }

   322 

   323     // Get the schema and tablename for the old table.

   324     $old_full_name = $this->connection->prefixTables('{' . $table . '}');

   325     list($old_schema, $old_table_name) = strpos($old_full_name, '.') ? explode('.', $old_full_name) : array('public', $old_full_name);

   326 

   327     // Index names and constraint names are global in PostgreSQL, so we need to

   328     // rename them when renaming the table.

   329     $indexes = $this->connection->query('SELECT indexname FROM pg_indexes WHERE schemaname = :schema AND tablename = :table', array(':schema' => $old_schema, ':table' => $old_table_name));

   330     foreach ($indexes as $index) {

   331       if (preg_match('/^' . preg_quote($old_full_name) . '_(.*)$/', $index->indexname, $matches)) {

   332         $index_name = $matches[1];

   333         $this->connection->query('ALTER INDEX ' . $index->indexname . ' RENAME TO {' . $new_name . '}_' . $index_name);

   334       }

   335     }

   336 

   337     // Now rename the table.

   338     // Ensure the new table name does not include schema syntax.

   339     $prefixInfo = $this->getPrefixInfo($new_name);

   340     $this->connection->query('ALTER TABLE {' . $table . '} RENAME TO ' . $prefixInfo['table']);

   341   }

   342 

   343   public function dropTable($table) {

   344     if (!$this->tableExists($table)) {

   345       return FALSE;

   346     }

   347 

   348     $this->connection->query('DROP TABLE {' . $table . '}');

   349     return TRUE;

   350   }

   351 

   352   public function addField($table, $field, $spec, $new_keys = array()) {

   353     if (!$this->tableExists($table)) {

   354       throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add field @table.@field: table doesn't exist.", array('@field' => $field, '@table' => $table)));

   355     }

   356     if ($this->fieldExists($table, $field)) {

   357       throw new DatabaseSchemaObjectExistsException(t("Cannot add field @table.@field: field already exists.", array('@field' => $field, '@table' => $table)));

   358     }

   359 

   360     $fixnull = FALSE;

   361     if (!empty($spec['not null']) && !isset($spec['default'])) {

   362       $fixnull = TRUE;

   363       $spec['not null'] = FALSE;

   364     }

   365     $query = 'ALTER TABLE {' . $table . '} ADD COLUMN ';

   366     $query .= $this->createFieldSql($field, $this->processField($spec));

   367     $this->connection->query($query);

   368     if (isset($spec['initial'])) {

   369       $this->connection->update($table)

   370         ->fields(array($field => $spec['initial']))

   371         ->execute();

   372     }

   373     if ($fixnull) {

   374       $this->connection->query("ALTER TABLE {" . $table . "} ALTER $field SET NOT NULL");

   375     }

   376     if (isset($new_keys)) {

   377       $this->_createKeys($table, $new_keys);

   378     }

   379     // Add column comment.

   380     if (!empty($spec['description'])) {

   381       $this->connection->query('COMMENT ON COLUMN {' . $table . '}.' . $field . ' IS ' . $this->prepareComment($spec['description']));

   382     }

   383   }

   384 

   385   public function dropField($table, $field) {

   386     if (!$this->fieldExists($table, $field)) {

   387       return FALSE;

   388     }

   389 

   390     $this->connection->query('ALTER TABLE {' . $table . '} DROP COLUMN "' . $field . '"');

   391     return TRUE;

   392   }

   393 

   394   public function fieldSetDefault($table, $field, $default) {

   395     if (!$this->fieldExists($table, $field)) {

   396       throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot set default value of field @table.@field: field doesn't exist.", array('@table' => $table, '@field' => $field)));

   397     }

   398 

   399     if (!isset($default)) {

   400       $default = 'NULL';

   401     }

   402     else {

   403       $default = is_string($default) ? "'$default'" : $default;

   404     }

   405 

   406     $this->connection->query('ALTER TABLE {' . $table . '} ALTER COLUMN "' . $field . '" SET DEFAULT ' . $default);

   407   }

   408 

   409   public function fieldSetNoDefault($table, $field) {

   410     if (!$this->fieldExists($table, $field)) {

   411       throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot remove default value of field @table.@field: field doesn't exist.", array('@table' => $table, '@field' => $field)));

   412     }

   413 

   414     $this->connection->query('ALTER TABLE {' . $table . '} ALTER COLUMN "' . $field . '" DROP DEFAULT');

   415   }

   416 

   417   public function indexExists($table, $name) {

   418     // Details http://www.postgresql.org/docs/8.3/interactive/view-pg-indexes.html

   419     $index_name = '{' . $table . '}_' . $name . '_idx';

   420     return (bool) $this->connection->query("SELECT 1 FROM pg_indexes WHERE indexname = '$index_name'")->fetchField();

   421   }

   422 

   423   /**

   424    * Helper function: check if a constraint (PK, FK, UK) exists.

   425    *

   426    * @param $table

   427    *   The name of the table.

   428    * @param $name

   429    *   The name of the constraint (typically 'pkey' or '[constraint]_key').

   430    */

   431   protected function constraintExists($table, $name) {

   432     $constraint_name = '{' . $table . '}_' . $name;

   433     return (bool) $this->connection->query("SELECT 1 FROM pg_constraint WHERE conname = '$constraint_name'")->fetchField();

   434   }

   435 

   436   public function addPrimaryKey($table, $fields) {

   437     if (!$this->tableExists($table)) {

   438       throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add primary key to table @table: table doesn't exist.", array('@table' => $table)));

   439     }

   440     if ($this->constraintExists($table, 'pkey')) {

   441       throw new DatabaseSchemaObjectExistsException(t("Cannot add primary key to table @table: primary key already exists.", array('@table' => $table)));

   442     }

   443 

   444     $this->connection->query('ALTER TABLE {' . $table . '} ADD PRIMARY KEY (' . implode(',', $fields) . ')');

   445   }

   446 

   447   public function dropPrimaryKey($table) {

   448     if (!$this->constraintExists($table, 'pkey')) {

   449       return FALSE;

   450     }

   451 

   452     $this->connection->query('ALTER TABLE {' . $table . '} DROP CONSTRAINT ' . $this->prefixNonTable($table, 'pkey'));

   453     return TRUE;

   454   }

   455 

   456   function addUniqueKey($table, $name, $fields) {

   457     if (!$this->tableExists($table)) {

   458       throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add unique key @name to table @table: table doesn't exist.", array('@table' => $table, '@name' => $name)));

   459     }

   460     if ($this->constraintExists($table, $name . '_key')) {

   461       throw new DatabaseSchemaObjectExistsException(t("Cannot add unique key @name to table @table: unique key already exists.", array('@table' => $table, '@name' => $name)));

   462     }

   463 

   464     $this->connection->query('ALTER TABLE {' . $table . '} ADD CONSTRAINT "' . $this->prefixNonTable($table, $name, 'key') . '" UNIQUE (' . implode(',', $fields) . ')');

   465   }

   466 

   467   public function dropUniqueKey($table, $name) {

   468     if (!$this->constraintExists($table, $name . '_key')) {

   469       return FALSE;

   470     }

   471 

   472     $this->connection->query('ALTER TABLE {' . $table . '} DROP CONSTRAINT "' . $this->prefixNonTable($table, $name, 'key') . '"');

   473     return TRUE;

   474   }

   475 

   476   public function addIndex($table, $name, $fields) {

   477     if (!$this->tableExists($table)) {

   478       throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add index @name to table @table: table doesn't exist.", array('@table' => $table, '@name' => $name)));

   479     }

   480     if ($this->indexExists($table, $name)) {

   481       throw new DatabaseSchemaObjectExistsException(t("Cannot add index @name to table @table: index already exists.", array('@table' => $table, '@name' => $name)));

   482     }

   483 

   484     $this->connection->query($this->_createIndexSql($table, $name, $fields));

   485   }

   486 

   487   public function dropIndex($table, $name) {

   488     if (!$this->indexExists($table, $name)) {

   489       return FALSE;

   490     }

   491 

   492     $this->connection->query('DROP INDEX ' . $this->prefixNonTable($table, $name, 'idx'));

   493     return TRUE;

   494   }

   495 

   496   public function changeField($table, $field, $field_new, $spec, $new_keys = array()) {

   497     if (!$this->fieldExists($table, $field)) {

   498       throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot change the definition of field @table.@name: field doesn't exist.", array('@table' => $table, '@name' => $field)));

   499     }

   500     if (($field != $field_new) && $this->fieldExists($table, $field_new)) {

   501       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)));

   502     }

   503 

   504     $spec = $this->processField($spec);

   505 

   506     // We need to typecast the new column to best be able to transfer the data

   507     // Schema_pgsql::getFieldTypeMap() will return possibilities that are not

   508     // 'cast-able' such as 'serial' - so they need to be casted int instead.

   509     if (in_array($spec['pgsql_type'], array('serial', 'bigserial', 'numeric'))) {

   510       $typecast = 'int';

   511     }

   512     else {

   513       $typecast = $spec['pgsql_type'];

   514     }

   515 

   516     if (in_array($spec['pgsql_type'], array('varchar', 'character', 'text')) && isset($spec['length'])) {

   517       $typecast .= '(' . $spec['length'] . ')';

   518     }

   519     elseif (isset($spec['precision']) && isset($spec['scale'])) {

   520       $typecast .= '(' . $spec['precision'] . ', ' . $spec['scale'] . ')';

   521     }

   522 

   523     // Remove old check constraints.

   524     $field_info = $this->queryFieldInformation($table, $field);

   525 

   526     foreach ($field_info as $check) {

   527       $this->connection->query('ALTER TABLE {' . $table . '} DROP CONSTRAINT "' . $check . '"');

   528     }

   529 

   530     // Remove old default.

   531     $this->fieldSetNoDefault($table, $field);

   532 

   533     $this->connection->query('ALTER TABLE {' . $table . '} ALTER "' . $field . '" TYPE ' . $typecast . ' USING "' . $field . '"::' . $typecast);

   534 

   535     if (isset($spec['not null'])) {

   536       if ($spec['not null']) {

   537         $nullaction = 'SET NOT NULL';

   538       }

   539       else {

   540         $nullaction = 'DROP NOT NULL';

   541       }

   542       $this->connection->query('ALTER TABLE {' . $table . '} ALTER "' . $field . '" ' . $nullaction);

   543     }

   544 

   545     if (in_array($spec['pgsql_type'], array('serial', 'bigserial'))) {

   546       // Type "serial" is known to PostgreSQL, but *only* during table creation,

   547       // not when altering. Because of that, the sequence needs to be created

   548       // and initialized by hand.

   549       $seq = "{" . $table . "}_" . $field_new . "_seq";

   550       $this->connection->query("CREATE SEQUENCE " . $seq);

   551       // Set sequence to maximal field value to not conflict with existing

   552       // entries.

   553       $this->connection->query("SELECT setval('" . $seq . "', MAX(\"" . $field . '")) FROM {' . $table . "}");

   554       $this->connection->query('ALTER TABLE {' . $table . '} ALTER "' . $field . '" SET DEFAULT nextval(\'' . $seq . '\')');

   555     }

   556 

   557     // Rename the column if necessary.

   558     if ($field != $field_new) {

   559       $this->connection->query('ALTER TABLE {' . $table . '} RENAME "' . $field . '" TO "' . $field_new . '"');

   560     }

   561 

   562     // Add unsigned check if necessary.

   563     if (!empty($spec['unsigned'])) {

   564       $this->connection->query('ALTER TABLE {' . $table . '} ADD CHECK ("' . $field_new . '" >= 0)');

   565     }

   566 

   567     // Add default if necessary.

   568     if (isset($spec['default'])) {

   569       $this->fieldSetDefault($table, $field_new, $spec['default']);

   570     }

   571 

   572     // Change description if necessary.

   573     if (!empty($spec['description'])) {

   574       $this->connection->query('COMMENT ON COLUMN {' . $table . '}."' . $field_new . '" IS ' . $this->prepareComment($spec['description']));

   575     }

   576 

   577     if (isset($new_keys)) {

   578       $this->_createKeys($table, $new_keys);

   579     }

   580   }

   581 

   582   protected function _createIndexSql($table, $name, $fields) {

   583     $query = 'CREATE INDEX "' . $this->prefixNonTable($table, $name, 'idx') . '" ON {' . $table . '} (';

   584     $query .= $this->_createKeySql($fields) . ')';

   585     return $query;

   586   }

   587 

   588   protected function _createKeys($table, $new_keys) {

   589     if (isset($new_keys['primary key'])) {

   590       $this->addPrimaryKey($table, $new_keys['primary key']);

   591     }

   592     if (isset($new_keys['unique keys'])) {

   593       foreach ($new_keys['unique keys'] as $name => $fields) {

   594         $this->addUniqueKey($table, $name, $fields);

   595       }

   596     }

   597     if (isset($new_keys['indexes'])) {

   598       foreach ($new_keys['indexes'] as $name => $fields) {

   599         $this->addIndex($table, $name, $fields);

   600       }

   601     }

   602   }

   603 

   604   /**

   605    * Retrieve a table or column comment.

   606    */

   607   public function getComment($table, $column = NULL) {

   608     $info = $this->getPrefixInfo($table);

   609     // Don't use {} around pg_class, pg_attribute tables.

   610     if (isset($column)) {

   611       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();

   612     }

   613     else {

   614       return $this->connection->query('SELECT obj_description(oid, ?) FROM pg_class WHERE relname = ?', array('pg_class', $info['table']))->fetchField();

   615     }

   616   }

   617 }