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MDL-46235 ddl: add support for large number of text fields in one database table

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Petr Skoda
2014-07-07 18:31:45 +12:00
parent e609e6cf02
commit a45d54b8cb
4 changed files with 478 additions and 0 deletions
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120
lib/ddl/mysql_sql_generator.php
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@@ -88,6 +88,9 @@ class mysql_sql_generator extends sql_generator {
/** @var string SQL sentence to rename one key 'TABLENAME', 'OLDKEYNAME' and 'NEWKEYNAME' are dynamically replaced.*/
public $rename_key_sql = null;
/** Maximum size of InnoDB row in Antelope file format */
const ANTELOPE_MAX_ROW_SIZE = 8126;
/**
* Reset a sequence to the id field of a table.
*
@@ -108,6 +111,78 @@ class mysql_sql_generator extends sql_generator {
return array("ALTER TABLE $this->prefix$tablename AUTO_INCREMENT = $value");
}
/**
* Calculate proximate row size when using InnoDB
* tables in Antelope row format.
*
* Note: the returned value is a bit higher to compensate for
* errors and changes of column data types.
*
* @param xmldb_field[]|database_column_info[] $columns
* @return int approximate row size in bytes
*/
public function guess_antolope_row_size(array $columns) {
if (empty($columns)) {
return 0;
}
$size = 0;
$first = reset($columns);
if (count($columns) > 1) {
// Do not start with zero because we need to cover changes of field types and
// this calculation is most probably not be accurate.
$size += 1000;
}
if ($first instanceof xmldb_field) {
foreach ($columns as $field) {
switch ($field->getType()) {
case XMLDB_TYPE_TEXT:
$size += 768;
break;
case XMLDB_TYPE_BINARY:
$size += 768;
break;
case XMLDB_TYPE_CHAR:
$bytes = $field->getLength() * 3;
if ($bytes > 768) {
$bytes = 768;
}
$size += $bytes;
break;
default:
// Anything else is usually maximum 8 bytes.
$size += 8;
}
}
} else if ($first instanceof database_column_info) {
foreach ($columns as $column) {
switch ($column->meta_type) {
case 'X':
$size += 768;
break;
case 'B':
$size += 768;
break;
case 'C':
$bytes = $column->max_length * 3;
if ($bytes > 768) {
$bytes = 768;
}
$size += $bytes;
break;
default:
// Anything else is usually maximum 8 bytes.
$size += 8;
}
}
}
return $size;
}
/**
* Given one correct xmldb_table, returns the SQL statements
* to create it (inside one array).
@@ -122,6 +197,15 @@ class mysql_sql_generator extends sql_generator {
// Do we know collation?
$collation = $this->mdb->get_dbcollation();
// Do we need to use compressed format for rows?
$rowformat = "";
$size = $this->guess_antolope_row_size($xmldb_table->getFields());
if ($size > self::ANTELOPE_MAX_ROW_SIZE) {
if ($this->mdb->is_compressed_row_format_supported()) {
$rowformat = "\n ROW_FORMAT=Compressed";
}
}
$sqlarr = parent::getCreateTableSQL($xmldb_table);
// This is a very nasty hack that tries to use just one query per created table
@@ -144,6 +228,9 @@ class mysql_sql_generator extends sql_generator {
}
$sql .= "\n DEFAULT COLLATE = $collation";
}
if ($rowformat) {
$sql .= $rowformat;
}
$sqls[] = $sql;
continue;
}
@@ -186,6 +273,39 @@ class mysql_sql_generator extends sql_generator {
return $sqls;
}
/**
* Given one xmldb_table and one xmldb_field, return the SQL statements needed to add the field to the table.
*
* @param xmldb_table $xmldb_table The table related to $xmldb_field.
* @param xmldb_field $xmldb_field The instance of xmldb_field to create the SQL from.
* @param string $skip_type_clause The type clause on alter columns, NULL by default.
* @param string $skip_default_clause The default clause on alter columns, NULL by default.
* @param string $skip_notnull_clause The null/notnull clause on alter columns, NULL by default.
* @return array The SQL statement for adding a field to the table.
*/
public function getAddFieldSQL($xmldb_table, $xmldb_field, $skip_type_clause = NULL, $skip_default_clause = NULL, $skip_notnull_clause = NULL) {
$sqls = parent::getAddFieldSQL($xmldb_table, $xmldb_field, $skip_type_clause, $skip_default_clause, $skip_notnull_clause);
if ($this->table_exists($xmldb_table)) {
$tablename = $xmldb_table->getName();
$size = $this->guess_antolope_row_size($this->mdb->get_columns($tablename));
$size += $this->guess_antolope_row_size(array($xmldb_field));
if ($size > self::ANTELOPE_MAX_ROW_SIZE) {
if ($this->mdb->is_compressed_row_format_supported()) {
$format = strtolower($this->mdb->get_row_format($tablename));
if ($format === 'compact' or $format === 'redundant') {
// Change the format before conversion so that we do not run out of space.
array_unshift($sqls, "ALTER TABLE {$this->prefix}$tablename ROW_FORMAT=Compressed");
}
}
}
}
return $sqls;
}
/**
* Given one correct xmldb_table, returns the SQL statements
* to create temporary table (inside one array).