added postgresql features to reset seq/check integrity

[Ragazzo]

Added some new features for postgresql. I also raised visibility of extremely useful method findTablesNames. Since it is different per database and user can not have one sql this method is very useful. I also enabled emulating prepare as i've described in comment.
@qiangxue please review when you will have time

[Ragazzo]

tested it locally on database with several tables, works well, but to be sure can be tested by some other developers. Later maybe will provide tests (for now i am a little bit not known how to setup database for them in fw tests).

[Ragazzo]

related with #1646

[Ragazzo]

fixed some bugs. ready for review.

[samdark]

Please fix code style.

[qiangxue]

Looks good to me. Please fix the coding style pointed out by @samdark and also add a line to CHANGELOG. I will then merge it. Thanks!

[Ragazzo]

i also have small question, i've ported it from Yii1, so there was

if(strpos($sequence,'.')!==false)

and

if(strpos($tableName,'.')!==false)

to be true i dont remember when in postgresql schema can contain ., for table name in ``checkIntegrityit can be but we already specified schema in this method,is this checks needed and correct? Never saw this) Also why we$key = reset($table->primaryKey);` reset pk if it is still contain the same columns for table (this was taken from mysql query-builder of Yii2)?

[qiangxue]

I'm not sure about if(strpos($sequence,'.')!==false).

For if(strpos($tableName,'.')!==false), you are right that we don't need this check in 2.0. In 1.1, we need it because findTableNames() return table names prefixed with schema names.

$key = reset($table->primaryKey) gets the first column in the primary key. What's wrong with this?

[Ragazzo]

I'm not sure about if(strpos($sequence,'.')!==false).

ok, then will leave it for any case.

For if(strpos($tableName,'.')!==false), you are right that we don't need this check in 2.0. In 1.1, we need it because findTableNames() return table names prefixed with schema names.

right, so maybe we need to make this:

#in checkIntegrity method
$schema = $schema ? $schema : $this->db->schema->defaultSchema;

#in foreach cycle
$tableName='"'.$schema.".".$tableName.'"';

or dont needed?

$key = reset($table->primaryKey) gets the first column in the primary key. What's wrong with this?

right, my misunderstanding.

[qiangxue]

Sounds good to me.

[Ragazzo]

ok, so since `"ALTER TABLE "public"."tbl_user_profile" ENABLE TRIGGER ALL; "`` is valid in pgsql, will make changes according to the discussion and submit new push here.

[Ragazzo]

done, ready for review.

[qiangxue]

Thanks!