Merge pull request #100 from PostgreSQL-For-Wordpress/site-health

add rewrite logic for SHOW TABLE STATUS and a catch for calls to information_schema

pg4wp/driver_pgsql_rewrite.php

@@ -12,7 +12,7 @@
 function createSQLRewriter(string $sql): AbstractSQLRewriter
 {
     $sql = trim($sql);
-    if (preg_match('/^(SELECT|INSERT|REPLACE INTO|UPDATE|DELETE|DESCRIBE|ALTER TABLE|CREATE TABLE|DROP TABLE|SHOW INDEX|SHOW VARIABLES|SHOW TABLES|OPTIMIZE TABLE|SET NAMES|SHOW FULL COLUMNS)\b/i', $sql, $matches)) {
+    if (preg_match('/^(SELECT|INSERT|REPLACE INTO|UPDATE|DELETE|DESCRIBE|ALTER TABLE|CREATE TABLE|DROP TABLE|SHOW INDEX|SHOW VARIABLES|SHOW TABLES|OPTIMIZE TABLE|SET NAMES|SHOW FULL COLUMNS|SHOW TABLE STATUS)\b/i', $sql, $matches)) {
         // Convert to a format suitable for class names (e.g., "SHOW TABLES" becomes "ShowTables")
         $type = str_replace(' ', '', ucwords(str_replace('_', ' ', strtolower($matches[1]))));
         $className = $type . 'SQLRewriter';

pg4wp/rewriters/DescribeSQLRewriter.php

@@ -28,9 +28,10 @@ protected function extractTableName($sql)
      * Generates a PostgreSQL-compatible SQL query to mimic MySQL's "DESCRIBE".
      *
      * @param string $tableName The table name
+     * @param string $schema The schema name
      * @return string The generated SQL query
      */
-    public function generatePostgresDescribeTable($tableName)
+    public function generatePostgresDescribeTable($tableName, $schema = "public")
     {
         $sql = <<<SQL
             SELECT  
@@ -70,7 +71,7 @@ public function generatePostgresDescribeTable($tableName)
                 LEFT JOIN pg_constraint p ON p.conrelid = c.oid AND f.attnum = ANY (p.conkey)  
                 LEFT JOIN pg_class AS g ON p.confrelid = g.oid  
             WHERE c.relkind = 'r'::char  
-                AND n.nspname = 'public' 
+                AND n.nspname = '$schema' 
                 AND c.relname = '$tableName'
                 AND f.attnum > 0 ORDER BY number
         SQL;

pg4wp/rewriters/SelectSQLRewriter.php

@@ -34,6 +34,16 @@ public function rewrite(): string
             $sql = preg_replace('/SELECT\s+.*?\s+FROM\s+/is', 'SELECT COUNT(*) FROM ', $sql, 1);
         }
 
+        if(false !== strpos($sql, 'information_schema')) {
+            // WP Site Health rewrites
+            if (false !== strpos($sql, "SELECT TABLE_NAME AS 'table', TABLE_ROWS AS 'rows', SUM(data_length + index_length)")) {
+                $sql = $this->postgresTableSizeRewrite(); 
+                return $sql;
+            }
+
+            throw new Exception("Unsupported call to information_schema, this probably won't work correctly and needs to be specifically handled, open a github issue with the SQL");
+        }
+
         $sql = $this->ensureOrderByInSelect($sql);
 
         // Convert CONVERT to CAST
@@ -350,4 +360,29 @@ protected function convertToPostgresLimitSyntax($sql)
         return $sql;
     }
 
+    // This method is specifically to handle should_suggest_persistent_object_cache in wp site health
+    protected function postgresTableSizeRewrite($schema = 'public') 
+    {
+
+        $sql = <<<SQL
+        SELECT 
+            C.relname AS "table", 
+            S.n_live_tup AS "rows", 
+            pg_total_relation_size(C.oid) AS "bytes"
+        FROM 
+            pg_class C 
+        LEFT JOIN 
+            pg_namespace N ON (N.oid = C.relnamespace) 
+        INNER JOIN 
+            pg_stat_user_tables S ON (S.relid = C.oid) 
+        WHERE 
+            N.nspname = '$schema' AND 
+            C.relname IN ('wp_comments','wp_options','wp_posts','wp_terms','wp_users')
+        GROUP BY 
+            C.relname, pg_total_relation_size(C.oid), S.n_live_tup;
+        SQL;
+
+        return $sql;
+    }
+
 }

pg4wp/rewriters/ShowFullColumnsSQLRewriter.php

@@ -28,9 +28,10 @@ protected function extractTableNameFromShowColumns($sql)
      * Generates a PostgreSQL-compatible SQL query to mimic MySQL's "SHOW FULL COLUMNS".
      *
      * @param string $tableName The table name
+     * @param string $schema The schema name
      * @return string The generated SQL query
      */
-    public function generatePostgresShowColumns($tableName)
+    public function generatePostgresShowColumns($tableName, $schema = "public")
     {
         $sql = <<<SQL
             SELECT 
@@ -62,7 +63,7 @@ public function generatePostgresShowColumns($tableName)
                     FROM pg_catalog.pg_class c
                     LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
                     WHERE c.relname = '$tableName'
-                    AND n.nspname = 'public'
+                    AND n.nspname = '$schema'
                 )
             ORDER BY 
                 a.attnum;

pg4wp/rewriters/ShowTableStatusSQLRewriter.php

@@ -0,0 +1,54 @@
+<?php
+
+class ShowTableStatusSQLRewriter extends AbstractSQLRewriter
+{
+    public function rewrite(): string
+    {
+        $sql = $this->original();
+        return $this->generatePostgresShowTableStatus(); 
+    }
+
+
+    /**
+     * Generates a PostgreSQL-compatible SQL query to mimic MySQL's "SHOW TABLE STATUS".
+     *
+     * @return string The generated SQL query
+     */
+    public function generatePostgresShowTableStatus($schema = "public")
+    {
+        $sql = <<<SQL
+        SELECT 
+            'Postgres' AS Engine,
+            cls.relname AS TableName, 
+            NULL AS Version,
+            NULL AS Row_format,
+            cls.reltuples AS Rows,
+            NULL AS Avg_row_length,
+            pg_size_pretty(pg_relation_size(cls.oid)) AS Data_length,
+            NULL AS Max_data_length,
+            pg_size_pretty(pg_indexes_size(cls.oid)) AS Index_length, 
+            NULL AS Data_free,
+            NULL AS Auto_increment,
+            NULL AS Create_time,
+            NULL AS Update_time,
+            NULL AS Check_time,
+            'UTF8' AS Table_collation,
+            NULL AS Checksum,
+            NULL AS Create_options,
+            obj_description(cls.oid) AS Comment
+        FROM
+            pg_class cls
+        JOIN 
+            pg_namespace nsp ON cls.relnamespace = nsp.oid
+        WHERE 
+            cls.relkind = 'r' 
+            AND nsp.nspname NOT LIKE 'pg_%' 
+            AND nsp.nspname != 'information_schema' 
+            AND nsp.nspname = '$schema' 
+        ORDER BY 
+            cls.relname ASC;
+        SQL;
+
+        return $sql;
+    }
+}

pg4wp/rewriters/ShowTablesSQLRewriter.php

@@ -4,6 +4,7 @@ class ShowTablesSQLRewriter extends AbstractSQLRewriter
 {
     public function rewrite(): string
     {
-        return 'SELECT tablename FROM pg_tables WHERE schemaname = \'public\';';
+        $schema = "public";
+        return 'SELECT tablename FROM pg_tables WHERE schemaname = \'$schema\';';
     }
 }