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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Native pgsql class representing moodle database interface.
*
* @package core_dml
* @copyright 2008 Petr Skoda (http://skodak.org)
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
defined('MOODLE_INTERNAL') || die();
require_once(__DIR__.'/moodle_database.php');
require_once(__DIR__.'/pgsql_native_moodle_recordset.php');
require_once(__DIR__.'/pgsql_native_moodle_temptables.php');
/**
* Native pgsql class representing moodle database interface.
*
* @package core_dml
* @copyright 2008 Petr Skoda (http://skodak.org)
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class pgsql_native_moodle_database extends moodle_database {
/** @var resource $pgsql database resource */
protected $pgsql = null;
protected $last_error_reporting; // To handle pgsql driver default verbosity
/** @var bool savepoint hack for MDL-35506 - workaround for automatic transaction rollback on error */
protected $savepointpresent = false;
/** @var int Number of cursors used (for constructing a unique ID) */
protected $cursorcount = 0;
/** @var int Default number of rows to fetch at a time when using recordsets with cursors */
const DEFAULT_FETCH_BUFFER_SIZE = 100000;
/**
* Detects if all needed PHP stuff installed.
* Note: can be used before connect()
* @return mixed true if ok, string if something
*/
public function driver_installed() {
if (!extension_loaded('pgsql')) {
return get_string('pgsqlextensionisnotpresentinphp', 'install');
}
return true;
}
/**
* Returns database family type - describes SQL dialect
* Note: can be used before connect()
* @return string db family name (mysql, postgres, mssql, oracle, etc.)
*/
public function get_dbfamily() {
return 'postgres';
}
/**
* Returns more specific database driver type
* Note: can be used before connect()
* @return string db type mysqli, pgsql, oci, mssql, sqlsrv
*/
protected function get_dbtype() {
return 'pgsql';
}
/**
* Returns general database library name
* Note: can be used before connect()
* @return string db type pdo, native
*/
protected function get_dblibrary() {
return 'native';
}
/**
* Returns localised database type name
* Note: can be used before connect()
* @return string
*/
public function get_name() {
return get_string('nativepgsql', 'install');
}
/**
* Returns localised database configuration help.
* Note: can be used before connect()
* @return string
*/
public function get_configuration_help() {
return get_string('nativepgsqlhelp', 'install');
}
/**
* Connect to db
* Must be called before other methods.
* @param string $dbhost The database host.
* @param string $dbuser The database username.
* @param string $dbpass The database username's password.
* @param string $dbname The name of the database being connected to.
* @param mixed $prefix string means moodle db prefix, false used for external databases where prefix not used
* @param array $dboptions driver specific options
* @return bool true
* @throws dml_connection_exception if error
*/
public function connect($dbhost, $dbuser, $dbpass, $dbname, $prefix, array $dboptions=null) {
if ($prefix == '' and !$this->external) {
//Enforce prefixes for everybody but mysql
throw new dml_exception('prefixcannotbeempty', $this->get_dbfamily());
}
$driverstatus = $this->driver_installed();
if ($driverstatus !== true) {
throw new dml_exception('dbdriverproblem', $driverstatus);
}
$this->store_settings($dbhost, $dbuser, $dbpass, $dbname, $prefix, $dboptions);
$pass = addcslashes($this->dbpass, "'\\");
// Unix socket connections should have lower overhead
if (!empty($this->dboptions['dbsocket']) and ($this->dbhost === 'localhost' or $this->dbhost === '127.0.0.1')) {
$connection = "user='$this->dbuser' password='$pass' dbname='$this->dbname'";
if (strpos($this->dboptions['dbsocket'], '/') !== false) {
// A directory was specified as the socket location.
$connection .= " host='".$this->dboptions['dbsocket']."'";
}
if (!empty($this->dboptions['dbport'])) {
// A port as specified, add it to the connection as it's used as part of the socket path.
$connection .= " port ='".$this->dboptions['dbport']."'";
}
} else {
$this->dboptions['dbsocket'] = '';
if (empty($this->dbname)) {
// probably old style socket connection - do not add port
$port = "";
} else if (empty($this->dboptions['dbport'])) {
$port = "port ='5432'";
} else {
$port = "port ='".$this->dboptions['dbport']."'";
}
$connection = "host='$this->dbhost' $port user='$this->dbuser' password='$pass' dbname='$this->dbname'";
}
if (empty($this->dboptions['dbhandlesoptions'])) {
// ALTER USER and ALTER DATABASE are overridden by these settings.
$options = array('--client_encoding=utf8', '--standard_conforming_strings=on');
// Select schema if specified, otherwise the first one wins.
if (!empty($this->dboptions['dbschema'])) {
$options[] = "-c search_path=" . addcslashes($this->dboptions['dbschema'], "'\\");
}
$connection .= " options='" . implode(' ', $options) . "'";
}
ob_start();
if (empty($this->dboptions['dbpersist'])) {
$this->pgsql = pg_connect($connection, PGSQL_CONNECT_FORCE_NEW);
} else {
$this->pgsql = pg_pconnect($connection, PGSQL_CONNECT_FORCE_NEW);
}
$dberr = ob_get_contents();
ob_end_clean();
$status = pg_connection_status($this->pgsql);
if ($status === false or $status === PGSQL_CONNECTION_BAD) {
$this->pgsql = null;
throw new dml_connection_exception($dberr);
}
if (!empty($this->dboptions['dbpersist'])) {
// There are rare situations (such as PHP out of memory errors) when open cursors may
// not be closed at the end of a connection. When using persistent connections, the
// cursors remain open and 'get in the way' of future connections. To avoid this
// problem, close all cursors here.
$result = pg_query($this->pgsql, 'CLOSE ALL');
if ($result) {
pg_free_result($result);
}
}
if (!empty($this->dboptions['dbhandlesoptions'])) {
/* We don't trust people who just set the dbhandlesoptions, this code checks up on them.
* These functions do not talk to the server, they use the client library knowledge to determine state.
*/
if (!empty($this->dboptions['dbschema'])) {
throw new dml_connection_exception('You cannot specify a schema with dbhandlesoptions, use the database to set it.');
}
if (pg_client_encoding($this->pgsql) != 'UTF8') {
throw new dml_connection_exception('client_encoding = UTF8 not set, it is: ' . pg_client_encoding($this->pgsql));
}
if (pg_escape_string($this->pgsql, '\\') != '\\') {
throw new dml_connection_exception('standard_conforming_strings = on, must be set at the database.');
}
}
// Connection stabilised and configured, going to instantiate the temptables controller
$this->temptables = new pgsql_native_moodle_temptables($this);
return true;
}
/**
* Close database connection and release all resources
* and memory (especially circular memory references).
* Do NOT use connect() again, create a new instance if needed.
*/
public function dispose() {
parent::dispose(); // Call parent dispose to write/close session and other common stuff before closing connection
if ($this->pgsql) {
pg_close($this->pgsql);
$this->pgsql = null;
}
}
/**
* Called before each db query.
* @param string $sql
* @param array array of parameters
* @param int $type type of query
* @param mixed $extrainfo driver specific extra information
* @return void
*/
protected function query_start($sql, array $params=null, $type, $extrainfo=null) {
parent::query_start($sql, $params, $type, $extrainfo);
// pgsql driver tents to send debug to output, we do not need that ;-)
$this->last_error_reporting = error_reporting(0);
}
/**
* Called immediately after each db query.
* @param mixed db specific result
* @return void
*/
protected function query_end($result) {
// reset original debug level
error_reporting($this->last_error_reporting);
try {
parent::query_end($result);
if ($this->savepointpresent and $this->last_type != SQL_QUERY_AUX and $this->last_type != SQL_QUERY_SELECT) {
$res = @pg_query($this->pgsql, "RELEASE SAVEPOINT moodle_pg_savepoint; SAVEPOINT moodle_pg_savepoint");
if ($res) {
pg_free_result($res);
}
}
} catch (Exception $e) {
if ($this->savepointpresent) {
$res = @pg_query($this->pgsql, "ROLLBACK TO SAVEPOINT moodle_pg_savepoint; SAVEPOINT moodle_pg_savepoint");
if ($res) {
pg_free_result($res);
}
}
throw $e;
}
}
/**
* Returns database server info array
* @return array Array containing 'description' and 'version' info
*/
public function get_server_info() {
static $info;
if (!$info) {
$this->query_start("--pg_version()", null, SQL_QUERY_AUX);
$info = pg_version($this->pgsql);
$this->query_end(true);
}
return array('description'=>$info['server'], 'version'=>$info['server']);
}
/**
* Returns supported query parameter types
* @return int bitmask of accepted SQL_PARAMS_*
*/
protected function allowed_param_types() {
return SQL_PARAMS_DOLLAR;
}
/**
* Returns last error reported by database engine.
* @return string error message
*/
public function get_last_error() {
return pg_last_error($this->pgsql);
}
/**
* Return tables in database WITHOUT current prefix.
* @param bool $usecache if true, returns list of cached tables.
* @return array of table names in lowercase and without prefix
*/
public function get_tables($usecache=true) {
if ($usecache and $this->tables !== null) {
return $this->tables;
}
$this->tables = array();
$prefix = str_replace('_', '|_', $this->prefix);
$sql = "SELECT c.relname
FROM pg_catalog.pg_class c
JOIN pg_catalog.pg_namespace as ns ON ns.oid = c.relnamespace
WHERE c.relname LIKE '$prefix%' ESCAPE '|'
AND c.relkind = 'r'
AND (ns.nspname = current_schema() OR ns.oid = pg_my_temp_schema())";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);
if ($result) {
while ($row = pg_fetch_row($result)) {
$tablename = reset($row);
if ($this->prefix !== false && $this->prefix !== '') {
if (strpos($tablename, $this->prefix) !== 0) {
continue;
}
$tablename = substr($tablename, strlen($this->prefix));
}
$this->tables[$tablename] = $tablename;
}
pg_free_result($result);
}
return $this->tables;
}
/**
* Return table indexes - everything lowercased.
* @param string $table The table we want to get indexes from.
* @return array of arrays
*/
public function get_indexes($table) {
$indexes = array();
$tablename = $this->prefix.$table;
$sql = "SELECT i.*
FROM pg_catalog.pg_indexes i
JOIN pg_catalog.pg_namespace as ns ON ns.nspname = i.schemaname
WHERE i.tablename = '$tablename'
AND (i.schemaname = current_schema() OR ns.oid = pg_my_temp_schema())";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);
if ($result) {
while ($row = pg_fetch_assoc($result)) {
// The index definition could be generated schema-qualifying the target table name
// for safety, depending on the pgsql version (CVE-2018-1058).
if (!preg_match('/CREATE (|UNIQUE )INDEX ([^\s]+) ON (|'.$row['schemaname'].'\.)'.$tablename.' USING ([^\s]+) \(([^\)]+)\)/i', $row['indexdef'], $matches)) {
continue;
}
if ($matches[5] === 'id') {
continue;
}
$columns = explode(',', $matches[5]);
foreach ($columns as $k=>$column) {
$column = trim($column);
if ($pos = strpos($column, ' ')) {
// index type is separated by space
$column = substr($column, 0, $pos);
}
$columns[$k] = $this->trim_quotes($column);
}
$indexes[$row['indexname']] = array('unique'=>!empty($matches[1]),
'columns'=>$columns);
}
pg_free_result($result);
}
return $indexes;
}
/**
* Returns detailed information about columns in table. This information is cached internally.
* @param string $table name
* @param bool $usecache
* @return database_column_info[] array of database_column_info objects indexed with column names
*/
public function get_columns($table, $usecache=true) {
if ($usecache) {
if ($this->temptables->is_temptable($table)) {
if ($data = $this->get_temp_tables_cache()->get($table)) {
return $data;
}
} else {
if ($data = $this->get_metacache()->get($table)) {
return $data;
}
}
}
$structure = array();
$tablename = $this->prefix.$table;
$sql = "SELECT a.attnum, a.attname AS field, t.typname AS type, a.attlen, a.atttypmod, a.attnotnull, a.atthasdef,
CASE WHEN a.atthasdef THEN pg_catalog.pg_get_expr(d.adbin, d.adrelid) END AS adsrc
FROM pg_catalog.pg_class c
JOIN pg_catalog.pg_namespace as ns ON ns.oid = c.relnamespace
JOIN pg_catalog.pg_attribute a ON a.attrelid = c.oid
JOIN pg_catalog.pg_type t ON t.oid = a.atttypid
LEFT JOIN pg_catalog.pg_attrdef d ON (d.adrelid = c.oid AND d.adnum = a.attnum)
WHERE relkind = 'r' AND c.relname = '$tablename' AND c.reltype > 0 AND a.attnum > 0
AND (ns.nspname = current_schema() OR ns.oid = pg_my_temp_schema())
ORDER BY a.attnum";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);
if (!$result) {
return array();
}
while ($rawcolumn = pg_fetch_object($result)) {
$info = new stdClass();
$info->name = $rawcolumn->field;
$matches = null;
if ($rawcolumn->type === 'varchar') {
$info->type = 'varchar';
$info->meta_type = 'C';
$info->max_length = $rawcolumn->atttypmod - 4;
$info->scale = null;
$info->not_null = ($rawcolumn->attnotnull === 't');
$info->has_default = ($rawcolumn->atthasdef === 't');
if ($info->has_default) {
$parts = explode('::', $rawcolumn->adsrc);
if (count($parts) > 1) {
$info->default_value = reset($parts);
$info->default_value = trim($info->default_value, "'");
} else {
$info->default_value = $rawcolumn->adsrc;
}
} else {
$info->default_value = null;
}
$info->primary_key = false;
$info->binary = false;
$info->unsigned = null;
$info->auto_increment= false;
$info->unique = null;
} else if (preg_match('/int(\d)/i', $rawcolumn->type, $matches)) {
$info->type = 'int';
if (strpos($rawcolumn->adsrc, 'nextval') === 0) {
$info->primary_key = true;
$info->meta_type = 'R';
$info->unique = true;
$info->auto_increment= true;
$info->has_default = false;
} else {
$info->primary_key = false;
$info->meta_type = 'I';
$info->unique = null;
$info->auto_increment= false;
$info->has_default = ($rawcolumn->atthasdef === 't');
}
// Return number of decimals, not bytes here.
if ($matches[1] >= 8) {
$info->max_length = 18;
} else if ($matches[1] >= 4) {
$info->max_length = 9;
} else if ($matches[1] >= 2) {
$info->max_length = 4;
} else if ($matches[1] >= 1) {
$info->max_length = 2;
} else {
$info->max_length = 0;
}
$info->scale = null;
$info->not_null = ($rawcolumn->attnotnull === 't');
if ($info->has_default) {
// PG 9.5+ uses ::<TYPE> syntax for some defaults.
$parts = explode('::', $rawcolumn->adsrc);
if (count($parts) > 1) {
$info->default_value = reset($parts);
} else {
$info->default_value = $rawcolumn->adsrc;
}
$info->default_value = trim($info->default_value, "()'");
} else {
$info->default_value = null;
}
$info->binary = false;
$info->unsigned = false;
} else if ($rawcolumn->type === 'numeric') {
$info->type = $rawcolumn->type;
$info->meta_type = 'N';
$info->primary_key = false;
$info->binary = false;
$info->unsigned = null;
$info->auto_increment= false;
$info->unique = null;
$info->not_null = ($rawcolumn->attnotnull === 't');
$info->has_default = ($rawcolumn->atthasdef === 't');
if ($info->has_default) {
// PG 9.5+ uses ::<TYPE> syntax for some defaults.
$parts = explode('::', $rawcolumn->adsrc);
if (count($parts) > 1) {
$info->default_value = reset($parts);
} else {
$info->default_value = $rawcolumn->adsrc;
}
$info->default_value = trim($info->default_value, "()'");
} else {
$info->default_value = null;
}
$info->max_length = $rawcolumn->atttypmod >> 16;
$info->scale = ($rawcolumn->atttypmod & 0xFFFF) - 4;
} else if (preg_match('/float(\d)/i', $rawcolumn->type, $matches)) {
$info->type = 'float';
$info->meta_type = 'N';
$info->primary_key = false;
$info->binary = false;
$info->unsigned = null;
$info->auto_increment= false;
$info->unique = null;
$info->not_null = ($rawcolumn->attnotnull === 't');
$info->has_default = ($rawcolumn->atthasdef === 't');
if ($info->has_default) {
// PG 9.5+ uses ::<TYPE> syntax for some defaults.
$parts = explode('::', $rawcolumn->adsrc);
if (count($parts) > 1) {
$info->default_value = reset($parts);
} else {
$info->default_value = $rawcolumn->adsrc;
}
$info->default_value = trim($info->default_value, "()'");
} else {
$info->default_value = null;
}
// just guess expected number of deciaml places :-(
if ($matches[1] == 8) {
// total 15 digits
$info->max_length = 8;
$info->scale = 7;
} else {
// total 6 digits
$info->max_length = 4;
$info->scale = 2;
}
} else if ($rawcolumn->type === 'text') {
$info->type = $rawcolumn->type;
$info->meta_type = 'X';
$info->max_length = -1;
$info->scale = null;
$info->not_null = ($rawcolumn->attnotnull === 't');
$info->has_default = ($rawcolumn->atthasdef === 't');
if ($info->has_default) {
$parts = explode('::', $rawcolumn->adsrc);
if (count($parts) > 1) {
$info->default_value = reset($parts);
$info->default_value = trim($info->default_value, "'");
} else {
$info->default_value = $rawcolumn->adsrc;
}
} else {
$info->default_value = null;
}
$info->primary_key = false;
$info->binary = false;
$info->unsigned = null;
$info->auto_increment= false;
$info->unique = null;
} else if ($rawcolumn->type === 'bytea') {
$info->type = $rawcolumn->type;
$info->meta_type = 'B';
$info->max_length = -1;
$info->scale = null;
$info->not_null = ($rawcolumn->attnotnull === 't');
$info->has_default = false;
$info->default_value = null;
$info->primary_key = false;
$info->binary = true;
$info->unsigned = null;
$info->auto_increment= false;
$info->unique = null;
}
$structure[$info->name] = new database_column_info($info);
}
pg_free_result($result);
if ($usecache) {
if ($this->temptables->is_temptable($table)) {
$this->get_temp_tables_cache()->set($table, $structure);
} else {
$this->get_metacache()->set($table, $structure);
}
}
return $structure;
}
/**
* Normalise values based in RDBMS dependencies (booleans, LOBs...)
*
* @param database_column_info $column column metadata corresponding with the value we are going to normalise
* @param mixed $value value we are going to normalise
* @return mixed the normalised value
*/
protected function normalise_value($column, $value) {
$this->detect_objects($value);
if (is_bool($value)) { // Always, convert boolean to int
$value = (int)$value;
} else if ($column->meta_type === 'B') {
if (!is_null($value)) {
// standard_conforming_strings must be enabled, otherwise pg_escape_bytea() will double escape
// \ and produce data errors. This is set on the connection.
$value = pg_escape_bytea($this->pgsql, $value);
}
} else if ($value === '') {
if ($column->meta_type === 'I' or $column->meta_type === 'F' or $column->meta_type === 'N') {
$value = 0; // prevent '' problems in numeric fields
}
}
return $value;
}
/**
* Is db in unicode mode?
* @return bool
*/
public function setup_is_unicodedb() {
// Get PostgreSQL server_encoding value
$sql = "SHOW server_encoding";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);
if (!$result) {
return false;
}
$rawcolumn = pg_fetch_object($result);
$encoding = $rawcolumn->server_encoding;
pg_free_result($result);
return (strtoupper($encoding) == 'UNICODE' || strtoupper($encoding) == 'UTF8');
}
/**
* Do NOT use in code, to be used by database_manager only!
* @param string|array $sql query
* @param array|null $tablenames an array of xmldb table names affected by this request.
* @return bool true
* @throws ddl_change_structure_exception A DDL specific exception is thrown for any errors.
*/
public function change_database_structure($sql, $tablenames = null) {
$this->get_manager(); // Includes DDL exceptions classes ;-)
if (is_array($sql)) {
$sql = implode("\n;\n", $sql);
}
if (!$this->is_transaction_started()) {
// It is better to do all or nothing, this helps with recovery...
$sql = "BEGIN ISOLATION LEVEL SERIALIZABLE;\n$sql\n; COMMIT";
}
try {
$this->query_start($sql, null, SQL_QUERY_STRUCTURE);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);
pg_free_result($result);
} catch (ddl_change_structure_exception $e) {
if (!$this->is_transaction_started()) {
$result = @pg_query($this->pgsql, "ROLLBACK");
@pg_free_result($result);
}
$this->reset_caches($tablenames);
throw $e;
}
$this->reset_caches($tablenames);
return true;
}
/**
* Execute general sql query. Should be used only when no other method suitable.
* Do NOT use this to make changes in db structure, use database_manager methods instead!
* @param string $sql query
* @param array $params query parameters
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function execute($sql, array $params=null) {
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
if (strpos($sql, ';') !== false) {
throw new coding_exception('moodle_database::execute() Multiple sql statements found or bound parameters not used properly in query!');
}
$this->query_start($sql, $params, SQL_QUERY_UPDATE);
$result = pg_query_params($this->pgsql, $sql, $params);
$this->query_end($result);
pg_free_result($result);
return true;
}
/**
* Get a number of records as a moodle_recordset using a SQL statement.
*
* Since this method is a little less readable, use of it should be restricted to
* code where it's possible there might be large datasets being returned. For known
* small datasets use get_records_sql - it leads to simpler code.
*
* The return type is like:
* @see function get_recordset.
*
* @param string $sql the SQL select query to execute.
* @param array $params array of sql parameters
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return moodle_recordset instance
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function get_recordset_sql($sql, array $params=null, $limitfrom=0, $limitnum=0) {
list($limitfrom, $limitnum) = $this->normalise_limit_from_num($limitfrom, $limitnum);
if ($limitnum) {
$sql .= " LIMIT $limitnum";
}
if ($limitfrom) {
$sql .= " OFFSET $limitfrom";
}
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
$this->query_start($sql, $params, SQL_QUERY_SELECT);
// For any query that doesn't explicitly specify a limit, we must use cursors to stop it
// loading the entire thing (unless the config setting is turned off).
$usecursors = !$limitnum && ($this->get_fetch_buffer_size() > 0);
if ($usecursors) {
// Work out the cursor unique identifer. This is based on a simple count used which
// should be OK because the identifiers only need to be unique within the current
// transaction.
$this->cursorcount++;
$cursorname = 'crs' . $this->cursorcount;
// Do the query to a cursor.
$sql = 'DECLARE ' . $cursorname . ' NO SCROLL CURSOR WITH HOLD FOR ' . $sql;
$result = pg_query_params($this->pgsql, $sql, $params);
} else {
$result = pg_query_params($this->pgsql, $sql, $params);
$cursorname = '';
}
$this->query_end($result);
if ($usecursors) {
pg_free_result($result);
$result = null;
}
return new pgsql_native_moodle_recordset($result, $this, $cursorname);
}
/**
* Gets size of fetch buffer used for recordset queries.
*
* If this returns 0 then cursors will not be used, meaning recordset queries will occupy enough
* memory as needed for the Postgres library to hold the entire query results in memory.
*
* @return int Fetch buffer size or 0 indicating not to use cursors
*/
protected function get_fetch_buffer_size() {
if (array_key_exists('fetchbuffersize', $this->dboptions)) {
return (int)$this->dboptions['fetchbuffersize'];
} else {
return self::DEFAULT_FETCH_BUFFER_SIZE;
}
}
/**
* Retrieves data from cursor. For use by recordset only; do not call directly.
*
* Return value contains the next batch of Postgres data, and a boolean indicating if this is
* definitely the last batch (if false, there may be more)
*
* @param string $cursorname Name of cursor to read from
* @return array Array with 2 elements (next data batch and boolean indicating last batch)
*/
public function fetch_from_cursor($cursorname) {
$count = $this->get_fetch_buffer_size();
$sql = 'FETCH ' . $count . ' FROM ' . $cursorname;
$this->query_start($sql, [], SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$last = pg_num_rows($result) !== $count;
$this->query_end($result);
return [$result, $last];
}
/**
* Closes a cursor. For use by recordset only; do not call directly.
*
* @param string $cursorname Name of cursor to close
* @return bool True if we actually closed one, false if the transaction was cancelled
*/
public function close_cursor($cursorname) {
// If the transaction got cancelled, then ignore this request.
$sql = 'CLOSE ' . $cursorname;
$this->query_start($sql, [], SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);
if ($result) {
pg_free_result($result);
}
return true;
}
/**
* Get a number of records as an array of objects using a SQL statement.
*
* Return value is like:
* @see function get_records.
*
* @param string $sql the SQL select query to execute. The first column of this SELECT statement
* must be a unique value (usually the 'id' field), as it will be used as the key of the
* returned array.
* @param array $params array of sql parameters
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return array of objects, or empty array if no records were found
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function get_records_sql($sql, array $params = null, $limitfrom = 0, $limitnum = 0) {
list($limitfrom, $limitnum) = $this->normalise_limit_from_num($limitfrom, $limitnum);
if ($limitnum) {
$sql .= " LIMIT $limitnum";
}
if ($limitfrom) {
$sql .= " OFFSET $limitfrom";
}
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
$this->query_start($sql, $params, SQL_QUERY_SELECT);
$result = pg_query_params($this->pgsql, $sql, $params);
$this->query_end($result);
// find out if there are any blobs
$numfields = pg_num_fields($result);
$blobs = array();
for ($i = 0; $i < $numfields; $i++) {
$type = pg_field_type($result, $i);
if ($type == 'bytea') {
$blobs[] = pg_field_name($result, $i);
}
}
$return = [];
while ($row = pg_fetch_assoc($result)) {
$id = reset($row);
if ($blobs) {
foreach ($blobs as $blob) {
$row[$blob] = ($row[$blob] !== null ? pg_unescape_bytea($row[$blob]) : null);
}
}
if (isset($return[$id])) {
$colname = key($row);
debugging("Did you remember to make the first column something unique in your call to get_records? Duplicate value '$id' found in column '$colname'.", DEBUG_DEVELOPER);
}
$return[$id] = (object) $row;
}
return $return;
}
/**
* Selects records and return values (first field) as an array using a SQL statement.
*
* @param string $sql The SQL query
* @param array $params array of sql parameters
* @return array of values
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function get_fieldset_sql($sql, array $params=null) {
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
$this->query_start($sql, $params, SQL_QUERY_SELECT);
$result = pg_query_params($this->pgsql, $sql, $params);
$this->query_end($result);
$return = pg_fetch_all_columns($result, 0);
if (pg_field_type($result, 0) == 'bytea') {
foreach ($return as $key => $value) {
$return[$key] = ($value === null ? $value : pg_unescape_bytea($value));
}
}
pg_free_result($result);
return $return;
}
/**
* Insert new record into database, as fast as possible, no safety checks, lobs not supported.
* @param string $table name
* @param mixed $params data record as object or array
* @param bool $returnit return it of inserted record
* @param bool $bulk true means repeated inserts expected
* @param bool $customsequence true if 'id' included in $params, disables $returnid
* @return bool|int true or new id
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function insert_record_raw($table, $params, $returnid=true, $bulk=false, $customsequence=false) {
if (!is_array($params)) {
$params = (array)$params;
}
$returning = "";
if ($customsequence) {
if (!isset($params['id'])) {
throw new coding_exception('moodle_database::insert_record_raw() id field must be specified if custom sequences used.');
}
$returnid = false;
} else {
if ($returnid) {
$returning = "RETURNING id";
unset($params['id']);
} else {
unset($params['id']);
}
}
if (empty($params)) {
throw new coding_exception('moodle_database::insert_record_raw() no fields found.');
}
$fields = implode(',', array_keys($params));
$values = array();
$i = 1;
foreach ($params as $value) {
$this->detect_objects($value);
$values[] = "\$".$i++;
}
$values = implode(',', $values);
$sql = "INSERT INTO {$this->prefix}$table ($fields) VALUES($values) $returning";
$this->query_start($sql, $params, SQL_QUERY_INSERT);
$result = pg_query_params($this->pgsql, $sql, $params);
$this->query_end($result);
if ($returning !== "") {
$row = pg_fetch_assoc($result);
$params['id'] = reset($row);
}
pg_free_result($result);
if (!$returnid) {
return true;
}
return (int)$params['id'];
}
/**
* Insert a record into a table and return the "id" field if required.
*
* Some conversions and safety checks are carried out. Lobs are supported.
* If the return ID isn't required, then this just reports success as true/false.
* $data is an object containing needed data
* @param string $table The database table to be inserted into
* @param object $data A data object with values for one or more fields in the record
* @param bool $returnid Should the id of the newly created record entry be returned? If this option is not requested then true/false is returned.
* @return bool|int true or new id
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function insert_record($table, $dataobject, $returnid=true, $bulk=false) {
$dataobject = (array)$dataobject;
$columns = $this->get_columns($table);
if (empty($columns)) {
throw new dml_exception('ddltablenotexist', $table);
}
$cleaned = array();
foreach ($dataobject as $field=>$value) {
if ($field === 'id') {
continue;
}
if (!isset($columns[$field])) {
continue;
}
$column = $columns[$field];
$cleaned[$field] = $this->normalise_value($column, $value);
}
return $this->insert_record_raw($table, $cleaned, $returnid, $bulk);
}
/**
* Insert multiple records into database as fast as possible.
*
* Order of inserts is maintained, but the operation is not atomic,
* use transactions if necessary.
*
* This method is intended for inserting of large number of small objects,
* do not use for huge objects with text or binary fields.
*
* @since Moodle 2.7
*
* @param string $table The database table to be inserted into
* @param array|Traversable $dataobjects list of objects to be inserted, must be compatible with foreach
* @return void does not return new record ids
*
* @throws coding_exception if data objects have different structure
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function insert_records($table, $dataobjects) {
if (!is_array($dataobjects) and !($dataobjects instanceof Traversable)) {
throw new coding_exception('insert_records() passed non-traversable object');
}
// PostgreSQL does not seem to have problems with huge queries.
$chunksize = 500;
if (!empty($this->dboptions['bulkinsertsize'])) {
$chunksize = (int)$this->dboptions['bulkinsertsize'];
}
$columns = $this->get_columns($table, true);
$fields = null;
$count = 0;
$chunk = array();
foreach ($dataobjects as $dataobject) {
if (!is_array($dataobject) and !is_object($dataobject)) {
throw new coding_exception('insert_records() passed invalid record object');
}
$dataobject = (array)$dataobject;
if ($fields === null) {
$fields = array_keys($dataobject);
$columns = array_intersect_key($columns, $dataobject);
unset($columns['id']);
} else if ($fields !== array_keys($dataobject)) {
throw new coding_exception('All dataobjects in insert_records() must have the same structure!');
}
$count++;
$chunk[] = $dataobject;
if ($count === $chunksize) {
$this->insert_chunk($table, $chunk, $columns);
$chunk = array();
$count = 0;
}
}
if ($count) {
$this->insert_chunk($table, $chunk, $columns);
}
}
/**
* Insert records in chunks, strict param types...
*
* Note: can be used only from insert_records().
*
* @param string $table
* @param array $chunk
* @param database_column_info[] $columns
*/
protected function insert_chunk($table, array $chunk, array $columns) {
$i = 1;
$params = array();
$values = array();
foreach ($chunk as $dataobject) {
$vals = array();
foreach ($columns as $field => $column) {
$params[] = $this->normalise_value($column, $dataobject[$field]);
$vals[] = "\$".$i++;
}
$values[] = '('.implode(',', $vals).')';
}
$fieldssql = '('.implode(',', array_keys($columns)).')';
$valuessql = implode(',', $values);
$sql = "INSERT INTO {$this->prefix}$table $fieldssql VALUES $valuessql";
$this->query_start($sql, $params, SQL_QUERY_INSERT);
$result = pg_query_params($this->pgsql, $sql, $params);
$this->query_end($result);
pg_free_result($result);
}
/**
* Import a record into a table, id field is required.
* Safety checks are NOT carried out. Lobs are supported.
*
* @param string $table name of database table to be inserted into
* @param object $dataobject A data object with values for one or more fields in the record
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function import_record($table, $dataobject) {
$dataobject = (array)$dataobject;
$columns = $this->get_columns($table);
$cleaned = array();
foreach ($dataobject as $field=>$value) {
$this->detect_objects($value);
if (!isset($columns[$field])) {
continue;
}
$column = $columns[$field];
$cleaned[$field] = $this->normalise_value($column, $value);
}
return $this->insert_record_raw($table, $cleaned, false, true, true);
}
/**
* Update record in database, as fast as possible, no safety checks, lobs not supported.
* @param string $table name
* @param mixed $params data record as object or array
* @param bool true means repeated updates expected
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function update_record_raw($table, $params, $bulk=false) {
$params = (array)$params;
if (!isset($params['id'])) {
throw new coding_exception('moodle_database::update_record_raw() id field must be specified.');
}
$id = $params['id'];
unset($params['id']);
if (empty($params)) {
throw new coding_exception('moodle_database::update_record_raw() no fields found.');
}
$i = 1;
$sets = array();
foreach ($params as $field=>$value) {
$this->detect_objects($value);
$sets[] = "$field = \$".$i++;
}
$params[] = $id; // last ? in WHERE condition
$sets = implode(',', $sets);
$sql = "UPDATE {$this->prefix}$table SET $sets WHERE id=\$".$i;
$this->query_start($sql, $params, SQL_QUERY_UPDATE);
$result = pg_query_params($this->pgsql, $sql, $params);
$this->query_end($result);
pg_free_result($result);
return true;
}
/**
* Update a record in a table
*
* $dataobject is an object containing needed data
* Relies on $dataobject having a variable "id" to
* specify the record to update
*
* @param string $table The database table to be checked against.
* @param object $dataobject An object with contents equal to fieldname=>fieldvalue. Must have an entry for 'id' to map to the table specified.
* @param bool true means repeated updates expected
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function update_record($table, $dataobject, $bulk=false) {
$dataobject = (array)$dataobject;
$columns = $this->get_columns($table);
$cleaned = array();
foreach ($dataobject as $field=>$value) {
if (!isset($columns[$field])) {
continue;
}
$column = $columns[$field];
$cleaned[$field] = $this->normalise_value($column, $value);
}
$this->update_record_raw($table, $cleaned, $bulk);
return true;
}
/**
* Set a single field in every table record which match a particular WHERE clause.
*
* @param string $table The database table to be checked against.
* @param string $newfield the field to set.
* @param string $newvalue the value to set the field to.
* @param string $select A fragment of SQL to be used in a where clause in the SQL call.
* @param array $params array of sql parameters
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function set_field_select($table, $newfield, $newvalue, $select, array $params=null) {
if ($select) {
$select = "WHERE $select";
}
if (is_null($params)) {
$params = array();
}
list($select, $params, $type) = $this->fix_sql_params($select, $params);
$i = count($params)+1;
// Get column metadata
$columns = $this->get_columns($table);
$column = $columns[$newfield];
$normalisedvalue = $this->normalise_value($column, $newvalue);
$newfield = "$newfield = \$" . $i;
$params[] = $normalisedvalue;
$sql = "UPDATE {$this->prefix}$table SET $newfield $select";
$this->query_start($sql, $params, SQL_QUERY_UPDATE);
$result = pg_query_params($this->pgsql, $sql, $params);
$this->query_end($result);
pg_free_result($result);
return true;
}
/**
* Delete one or more records from a table which match a particular WHERE clause, lobs not supported.
*
* @param string $table The database table to be checked against.
* @param string $select A fragment of SQL to be used in a where clause in the SQL call (used to define the selection criteria).
* @param array $params array of sql parameters
* @return bool true
* @throws dml_exception A DML specific exception is thrown for any errors.
*/
public function delete_records_select($table, $select, array $params=null) {
if ($select) {
$select = "WHERE $select";
}
$sql = "DELETE FROM {$this->prefix}$table $select";
list($sql, $params, $type) = $this->fix_sql_params($sql, $params);
$this->query_start($sql, $params, SQL_QUERY_UPDATE);
$result = pg_query_params($this->pgsql, $sql, $params);
$this->query_end($result);
pg_free_result($result);
return true;
}
/**
* Returns 'LIKE' part of a query.
*
* @param string $fieldname usually name of the table column
* @param string $param usually bound query parameter (?, :named)
* @param bool $casesensitive use case sensitive search
* @param bool $accensensitive use accent sensitive search (not all databases support accent insensitive)
* @param bool $notlike true means "NOT LIKE"
* @param string $escapechar escape char for '%' and '_'
* @return string SQL code fragment
*/
public function sql_like($fieldname, $param, $casesensitive = true, $accentsensitive = true, $notlike = false, $escapechar = '\\') {
if (strpos($param, '%') !== false) {
debugging('Potential SQL injection detected, sql_like() expects bound parameters (? or :named)');
}
// postgresql does not support accent insensitive text comparisons, sorry
if ($casesensitive) {
$LIKE = $notlike ? 'NOT LIKE' : 'LIKE';
} else {
$LIKE = $notlike ? 'NOT ILIKE' : 'ILIKE';
}
return "$fieldname $LIKE $param ESCAPE '$escapechar'";
}
public function sql_bitxor($int1, $int2) {
return '((' . $int1 . ') # (' . $int2 . '))';
}
public function sql_cast_char2int($fieldname, $text=false) {
return ' CAST(' . $fieldname . ' AS INT) ';
}
public function sql_cast_char2real($fieldname, $text=false) {
return " $fieldname::real ";
}
public function sql_concat() {
$arr = func_get_args();
$s = implode(' || ', $arr);
if ($s === '') {
return " '' ";
}
// Add always empty string element so integer-exclusive concats
// will work without needing to cast each element explicitly
return " '' || $s ";
}
public function sql_concat_join($separator="' '", $elements=array()) {
for ($n=count($elements)-1; $n > 0 ; $n--) {
array_splice($elements, $n, 0, $separator);
}
$s = implode(' || ', $elements);
if ($s === '') {
return " '' ";
}
return " $s ";
}
public function sql_regex_supported() {
return true;
}
public function sql_regex($positivematch = true, $casesensitive = false) {
if ($casesensitive) {
return $positivematch ? '~' : '!~';
} else {
return $positivematch ? '~*' : '!~*';
}
}
/**
* Does this driver support tool_replace?
*
* @since Moodle 2.6.1
* @return bool
*/
public function replace_all_text_supported() {
return true;
}
public function session_lock_supported() {
return true;
}
/**
* Obtain session lock
* @param int $rowid id of the row with session record
* @param int $timeout max allowed time to wait for the lock in seconds
* @return bool success
*/
public function get_session_lock($rowid, $timeout) {
// NOTE: there is a potential locking problem for database running
// multiple instances of moodle, we could try to use pg_advisory_lock(int, int),
// luckily there is not a big chance that they would collide
if (!$this->session_lock_supported()) {
return;
}
parent::get_session_lock($rowid, $timeout);
$timeoutmilli = $timeout * 1000;
$sql = "SET statement_timeout TO $timeoutmilli";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);
if ($result) {
pg_free_result($result);
}
$sql = "SELECT pg_advisory_lock($rowid)";
$this->query_start($sql, null, SQL_QUERY_AUX);
$start = time();
$result = pg_query($this->pgsql, $sql);
$end = time();
try {
$this->query_end($result);
} catch (dml_exception $ex) {
if ($end - $start >= $timeout) {
throw new dml_sessionwait_exception();
} else {
throw $ex;
}
}
if ($result) {
pg_free_result($result);
}
$sql = "SET statement_timeout TO DEFAULT";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);
if ($result) {
pg_free_result($result);
}
}
public function release_session_lock($rowid) {
if (!$this->session_lock_supported()) {
return;
}
if (!$this->used_for_db_sessions) {
return;
}
parent::release_session_lock($rowid);
$sql = "SELECT pg_advisory_unlock($rowid)";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);
if ($result) {
pg_free_result($result);
}
}
/**
* Driver specific start of real database transaction,
* this can not be used directly in code.
* @return void
*/
protected function begin_transaction() {
$this->savepointpresent = true;
$sql = "BEGIN ISOLATION LEVEL READ COMMITTED; SAVEPOINT moodle_pg_savepoint";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);
pg_free_result($result);
}
/**
* Driver specific commit of real database transaction,
* this can not be used directly in code.
* @return void
*/
protected function commit_transaction() {
$this->savepointpresent = false;
$sql = "RELEASE SAVEPOINT moodle_pg_savepoint; COMMIT";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);
pg_free_result($result);
}
/**
* Driver specific abort of real database transaction,
* this can not be used directly in code.
* @return void
*/
protected function rollback_transaction() {
$this->savepointpresent = false;
$sql = "RELEASE SAVEPOINT moodle_pg_savepoint; ROLLBACK";
$this->query_start($sql, null, SQL_QUERY_AUX);
$result = pg_query($this->pgsql, $sql);
$this->query_end($result);
pg_free_result($result);
}
/**
* Helper function trimming (whitespace + quotes) any string
* needed because PG uses to enclose with double quotes some
* fields in indexes definition and others
*
* @param string $str string to apply whitespace + quotes trim
* @return string trimmed string
*/
private function trim_quotes($str) {
return trim(trim($str), "'\"");
}
/**
* Postgresql supports full-text search indexes.
*
* @return bool
*/
public function is_fulltext_search_supported() {
return true;
}
}