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root / drupal7 / includes / database / pgsql / schema.inc @ bfb52287

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
}