framework/db/pgsql/Schema.php
protected function findColumns($table)
    {
        $tableName = $this->db->quoteValue($table->name);
        $schemaName = $this->db->quoteValue($table->schemaName);
        $sql = <<<SQL
SELECT
    d.nspname AS table_schema,
    c.relname AS table_name,
    a.attname AS column_name,
    COALESCE(td.typname, tb.typname, t.typname) AS data_type,
    COALESCE(td.typtype, tb.typtype, t.typtype) AS type_type,
    a.attlen AS character_maximum_length,
    pg_catalog.col_description(c.oid, a.attnum) AS column_comment,
    a.atttypmod AS modifier,
    a.attnotnull = false AS is_nullable,
    CAST(pg_get_expr(ad.adbin, ad.adrelid) AS varchar) AS column_default,
    coalesce(pg_get_expr(ad.adbin, ad.adrelid) ~ 'nextval',false) AS is_autoinc,
    CASE WHEN COALESCE(td.typtype, tb.typtype, t.typtype) = 'e'::char
        THEN array_to_string((SELECT array_agg(enumlabel) FROM pg_enum WHERE enumtypid = COALESCE(td.oid, tb.oid, a.atttypid))::varchar[], ',')
        ELSE NULL
    END AS enum_values,
    CASE atttypid
         WHEN 21 /*int2*/ THEN 16
         WHEN 23 /*int4*/ THEN 32
         WHEN 20 /*int8*/ THEN 64
         WHEN 1700 /*numeric*/ THEN
              CASE WHEN atttypmod = -1
               THEN null
               ELSE ((atttypmod - 4) >> 16) & 65535
               END
         WHEN 700 /*float4*/ THEN 24 /*FLT_MANT_DIG*/
         WHEN 701 /*float8*/ THEN 53 /*DBL_MANT_DIG*/
         ELSE null
      END   AS numeric_precision,
      CASE
        WHEN atttypid IN (21, 23, 20) THEN 0
        WHEN atttypid IN (1700) THEN
        CASE
            WHEN atttypmod = -1 THEN null
            ELSE (atttypmod - 4) & 65535
        END
           ELSE null
      END AS numeric_scale,
    CAST(
             information_schema._pg_char_max_length(information_schema._pg_truetypid(a, t), information_schema._pg_truetypmod(a, t))
             AS numeric
    ) AS size,
    a.attnum = any (ct.conkey) as is_pkey,
    COALESCE(NULLIF(a.attndims, 0), NULLIF(t.typndims, 0), (t.typcategory='A')::int) AS dimension
FROM
    pg_class c
    LEFT JOIN pg_attribute a ON a.attrelid = c.oid
    LEFT JOIN pg_attrdef ad ON a.attrelid = ad.adrelid AND a.attnum = ad.adnum
    LEFT JOIN pg_type t ON a.atttypid = t.oid
    LEFT JOIN pg_type tb ON (a.attndims > 0 OR t.typcategory='A') AND t.typelem > 0 AND t.typelem = tb.oid OR t.typbasetype > 0 AND t.typbasetype = tb.oid
    LEFT JOIN pg_type td ON t.typndims > 0 AND t.typbasetype > 0 AND tb.typelem = td.oid
    LEFT JOIN pg_namespace d ON d.oid = c.relnamespace
    LEFT JOIN pg_constraint ct ON ct.conrelid = c.oid AND ct.contype = 'p'
WHERE
    a.attnum > 0 AND t.typname != ''
    AND c.relname = {$tableName}
    AND d.nspname = {$schemaName}
ORDER BY
    a.attnum;
SQL;
        $columns = $this->db->createCommand($sql)->queryAll();
        if (empty($columns)) {
            return false;
        }
        foreach ($columns as $column) {
            if ($this->db->slavePdo->getAttribute(\PDO::ATTR_CASE) === \PDO::CASE_UPPER) {
                $column = array_change_key_case($column, CASE_LOWER);
            }
            $column = $this->loadColumnSchema($column);
            $table->columns[$column->name] = $column;
            if ($column->isPrimaryKey) {
                $table->primaryKey[] = $column->name;
                if ($table->sequenceName === null && preg_match("/nextval\\('\"?\\w+\"?\.?\"?\\w+\"?'(::regclass)?\\)/", $column->defaultValue) === 1) {
                    $table->sequenceName = preg_replace(['/nextval/', '/::/', '/regclass/', '/\'\)/', '/\(\'/'], '', $column->defaultValue);
                }
                $column->defaultValue = null;
            } elseif ($column->defaultValue) {
                if ($column->type === 'timestamp' && $column->defaultValue === 'now()') {
                    $column->defaultValue = new Expression($column->defaultValue);
                } elseif ($column->type === 'boolean') {
                    $column->defaultValue = ($column->defaultValue === 'true');
                } elseif (strncasecmp($column->dbType, 'bit', 3) === 0 || strncasecmp($column->dbType, 'varbit', 6) === 0) {
                    $column->defaultValue = bindec(trim($column->defaultValue, 'B\''));
                } elseif (preg_match("/^'(.*?)'::/", $column->defaultValue, $matches)) {
                    $column->defaultValue = $column->phpTypecast($matches[1]);
                } elseif (preg_match('/^(\()?(.*?)(?(1)\))(?:::.+)?$/', $column->defaultValue, $matches)) {
                    if ($matches[2] === 'NULL') {
                        $column->defaultValue = null;
                    } else {
                        $column->defaultValue = $column->phpTypecast($matches[2]);
                    }
                } else {
                    $column->defaultValue = $column->phpTypecast($column->defaultValue);
                }
            }
        }

        return true;
    }
protected function findColumns($table)
    {
        $tableName = $this->db->quoteValue($table->name);
        $schemaName = $this->db->quoteValue($table->schemaName);
        $sql = <<<SQL
SELECT
    d.nspname AS table_schema,
    c.relname AS table_name,
    a.attname AS column_name,
    COALESCE(td.typname, tb.typname, t.typname) AS data_type,
    COALESCE(td.typtype, tb.typtype, t.typtype) AS type_type,
    a.attlen AS character_maximum_length,
    pg_catalog.col_description(c.oid, a.attnum) AS column_comment,
    a.atttypmod AS modifier,
    a.attnotnull = false AS is_nullable,
    CAST(pg_get_expr(ad.adbin, ad.adrelid) AS varchar) AS column_default,
    coalesce(pg_get_expr(ad.adbin, ad.adrelid) ~ 'nextval',false) AS is_autoinc,
    CASE WHEN COALESCE(td.typtype, tb.typtype, t.typtype) = 'e'::char
        THEN array_to_string((SELECT array_agg(enumlabel) FROM pg_enum WHERE enumtypid = COALESCE(td.oid, tb.oid, a.atttypid))::varchar[], ',')
        ELSE NULL
    END AS enum_values,
    CASE atttypid
         WHEN 21 /*int2*/ THEN 16
         WHEN 23 /*int4*/ THEN 32
         WHEN 20 /*int8*/ THEN 64
         WHEN 1700 /*numeric*/ THEN
              CASE WHEN atttypmod = -1
               THEN null
               ELSE ((atttypmod - 4) >> 16) & 65535
               END
         WHEN 700 /*float4*/ THEN 24 /*FLT_MANT_DIG*/
         WHEN 701 /*float8*/ THEN 53 /*DBL_MANT_DIG*/
         ELSE null
      END   AS numeric_precision,
      CASE
        WHEN atttypid IN (21, 23, 20) THEN 0
        WHEN atttypid IN (1700) THEN
        CASE
            WHEN atttypmod = -1 THEN null
            ELSE (atttypmod - 4) & 65535
        END
           ELSE null
      END AS numeric_scale,
    CAST(
             information_schema._pg_char_max_length(information_schema._pg_truetypid(a, t), information_schema._pg_truetypmod(a, t))
             AS numeric
    ) AS size,
    a.attnum = any (ct.conkey) as is_pkey,
    COALESCE(NULLIF(a.attndims, 0), NULLIF(t.typndims, 0), (t.typcategory='A')::int) AS dimension
FROM
    pg_class c
    LEFT JOIN pg_attribute a ON a.attrelid = c.oid
    LEFT JOIN pg_attrdef ad ON a.attrelid = ad.adrelid AND a.attnum = ad.adnum
    LEFT JOIN pg_type t ON a.atttypid = t.oid
    LEFT JOIN pg_type tb ON (a.attndims > 0 OR t.typcategory='A') AND t.typelem > 0 AND t.typelem = tb.oid OR t.typbasetype > 0 AND t.typbasetype = tb.oid
    LEFT JOIN pg_type td ON t.typndims > 0 AND t.typbasetype > 0 AND tb.typelem = td.oid
    LEFT JOIN pg_namespace d ON d.oid = c.relnamespace
    LEFT JOIN pg_constraint ct ON ct.conrelid = c.oid AND ct.contype = 'p'
WHERE
    a.attnum > 0 AND t.typname != ''
    AND c.relname = {$tableName}
    AND d.nspname = {$schemaName}
ORDER BY
    a.attnum;
SQL;
        $columns = $this->db->createCommand($sql)->queryAll();
        if (empty($columns)) {
            return false;
        }
        foreach ($columns as $column) {
            if ($this->db->slavePdo->getAttribute(\PDO::ATTR_CASE) === \PDO::CASE_UPPER) {
                $column = array_change_key_case($column, CASE_LOWER);
            }
            $column = $this->loadColumnSchema($column);
            $table->columns[$column->name] = $column;
            if ($column->isPrimaryKey) {
                $table->primaryKey[] = $column->name;
                if ($table->sequenceName === null && preg_match("/nextval\\('\"?\\w+\"?\.?\"?\\w+\"?'(::regclass)?\\)/", $column->defaultValue) === 1) {
                    $table->sequenceName = preg_replace(['/nextval/', '/::/', '/regclass/', '/\'\)/', '/\(\'/'], '', $column->defaultValue);
                }
                $column->defaultValue = null;
            } elseif ($column->defaultValue) {
                if ($column->type === 'timestamp' && $column->defaultValue === 'now()') {
                    $column->defaultValue = new Expression($column->defaultValue);
                } elseif ($column->type === 'boolean') {
                    $column->defaultValue = ($column->defaultValue === 'true');
                } elseif (strncasecmp($column->dbType, 'bit', 3) === 0 || strncasecmp($column->dbType, 'varbit', 6) === 0) {
                    $column->defaultValue = bindec(trim($column->defaultValue, 'B\''));
                } elseif (preg_match("/^'(.*?)'::/", $column->defaultValue, $matches)) {
                    $column->defaultValue = $column->phpTypecast($matches[1]);
                } elseif (preg_match('/^(\()?(.*?)(?(1)\))(?:::.+)?$/', $column->defaultValue, $matches)) {
                    if ($matches[2] === 'NULL') {
                        $column->defaultValue = null;
                    } else {
                        $column->defaultValue = $column->phpTypecast($matches[2]);
                    }
                } else {
                    $column->defaultValue = $column->phpTypecast($column->defaultValue);
                }
            }
        }

        return true;
    }
Collects the metadata of table columns.
@param TableSchema $table the table metadata
@return bool whether the table exists in the database