Add two options: database and table

With the two new options, one can query any table he wants without recompiling the FDW. He also doesn't need to recompile to select another database. Most of the code come from the MySQL FDW written by Dave Page. Thanks to him. See https://github.com/dpage/mysql_fdw for more details.
gleu · Jun 6, 2013 · 292542c · 292542c
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commit 292542c
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diff --git a/THANKS.md b/THANKS.md
@@ -1 +1,3 @@
 Thanks to Andrew Dunstan for his blackhole foreign data wrapper. The sqlite foreign data wrapper is built upon his work.
+
+Thanks to Dave Page for this mysql foreign data wrapper. It helped me a lot to code some parts of this foreign data wrapper.
diff --git a/src/sqlite_fdw.c b/src/sqlite_fdw.c
@@ -24,6 +24,9 @@
 #include "optimizer/restrictinfo.h"
 
 #include "funcapi.h"
+#include "catalog/pg_foreign_server.h"
+#include "catalog/pg_foreign_table.h"
+#include "commands/defrem.h"
 #include "utils/rel.h"
 
 #include <sqlite3.h>
@@ -121,6 +124,12 @@ static bool sqliteAnalyzeForeignTable(Relation relation,
 							 BlockNumber *totalpages);
 #endif
 
+/*
+ * Helper functions
+ */
+static bool sqliteIsValidOption(const char *option, Oid context);
+static void sqliteGetOptions(Oid foreigntableid, char **database, char **table);
+
 /* 
  * structures used by the FDW 
  *
@@ -132,10 +141,26 @@ static bool sqliteAnalyzeForeignTable(Relation relation,
 /*
  * Describes the valid options for objects that use this wrapper.
  */
-struct sqliteFdwOption
+struct SQLiteFdwOption
 {
-	const char *optname;
-	Oid			optcontext;		/* Oid of catalog in which option may appear */
+	const char	*optname;
+	Oid		optcontext;	/* Oid of catalog in which option may appear */
+};
+
+/*
+ * Describes the valid options for objects that use this wrapper.
+ */
+static struct SQLiteFdwOption valid_options[] =
+{
+
+	/* Connection options */
+	{ "database",  ForeignServerRelationId },
+
+	/* Table options */
+	{ "table",     ForeignTableRelationId },
+
+	/* Sentinel */
+	{ NULL,			InvalidOid }
 };
 
 /*
@@ -209,23 +234,130 @@ sqlite_fdw_handler(PG_FUNCTION_ARGS)
 Datum
 sqlite_fdw_validator(PG_FUNCTION_ARGS)
 {
-	List	   *options_list = untransformRelOptions(PG_GETARG_DATUM(0));
+	List      *options_list = untransformRelOptions(PG_GETARG_DATUM(0));
+	Oid       catalog = PG_GETARG_OID(1);
+	char      *svr_database = NULL;
+	char      *svr_table = NULL;
+	ListCell  *cell;
 
 	elog(DEBUG1,"entering function %s",__func__);
 
-	/* make sure the options are valid */
+	/*
+	 * Check that only options supported by sqlite_fdw,
+	 * and allowed for the current object type, are given.
+	 */
+	foreach(cell, options_list)
+	{
+		DefElem	   *def = (DefElem *) lfirst(cell);
+
+		if (!sqliteIsValidOption(def->defname, catalog))
+		{
+			struct SQLiteFdwOption *opt;
+			StringInfoData buf;
+
+			/*
+			 * Unknown option specified, complain about it. Provide a hint
+			 * with list of valid options for the object.
+			 */
+			initStringInfo(&buf);
+			for (opt = valid_options; opt->optname; opt++)
+			{
+				if (catalog == opt->optcontext)
+					appendStringInfo(&buf, "%s%s", (buf.len > 0) ? ", " : "",
+							 opt->optname);
+			}
+
+			ereport(ERROR, 
+				(errcode(ERRCODE_FDW_INVALID_OPTION_NAME), 
+				errmsg("invalid option \"%s\"", def->defname), 
+				errhint("Valid options in this context are: %s", buf.len ? buf.data : "<none>")
+				));
+		}
 
-	/* no options are supported */
+		if (strcmp(def->defname, "database") == 0)
+		{
+			if (svr_database)
+				ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					errmsg("redundant options: database (%s)", defGetString(def))
+					));
 
-	if (list_length(options_list) > 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_FDW_INVALID_OPTION_NAME),
-				 errmsg("invalid options"),
-				 errhint("sqlite FDW does not support any options")));
+			svr_database = defGetString(def);
+		}
+		else if (strcmp(def->defname, "table") == 0)
+		{
+			if (svr_table)
+				ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					errmsg("redundant options: table (%s)", defGetString(def))
+					));
+
+			svr_table = defGetString(def);
+		}
+	}
 
 	PG_RETURN_VOID();
 }
 
+/*
+ * Check if the provided option is one of the valid options.
+ * context is the Oid of the catalog holding the object the option is for.
+ */
+static bool
+sqliteIsValidOption(const char *option, Oid context)
+{
+	struct SQLiteFdwOption *opt;
+
+	for (opt = valid_options; opt->optname; opt++)
+	{
+		if (context == opt->optcontext && strcmp(opt->optname, option) == 0)
+			return true;
+	}
+	return false;
+}
+
+/*
+ * Fetch the options for a mysql_fdw foreign table.
+ */
+static void
+sqliteGetOptions(Oid foreigntableid, char **database, char **table)
+{
+	ForeignTable   *f_table;
+	ForeignServer  *f_server;
+	List           *options;
+	ListCell       *lc;
+
+	/*
+	 * Extract options from FDW objects.
+	 */
+	f_table = GetForeignTable(foreigntableid);
+	f_server = GetForeignServer(f_table->serverid);
+
+	options = NIL;
+	options = list_concat(options, f_table->options);
+	options = list_concat(options, f_server->options);
+
+	/* Loop through the options */
+	foreach(lc, options)
+	{
+		DefElem *def = (DefElem *) lfirst(lc);
+
+		if (strcmp(def->defname, "database") == 0)
+			*database = defGetString(def);
+
+		if (strcmp(def->defname, "table") == 0)
+			*table = defGetString(def);
+	}
+
+	/* Check we have the options we need to proceed */
+	if (!*database && !*table)
+		ereport(ERROR,
+			(errcode(ERRCODE_SYNTAX_ERROR),
+			errmsg("a database and a table must be specified")
+			));
+}
+
+
 #if (PG_VERSION_NUM >= 90200)
 static void
 sqliteGetForeignRelSize(PlannerInfo *root,
@@ -376,22 +508,29 @@ sqliteBeginForeignScan(ForeignScanState *node,
 	 */
 	sqlite3                  *db;
 	SQLiteFdwExecutionState  *festate;
+	char                     *svr_database = NULL;
+	char                     *svr_table = NULL;
 	char                     *query;
+    size_t                   len;
 
 	elog(DEBUG1,"entering function %s",__func__);
 
+	/* Fetch options  */
+	sqliteGetOptions(RelationGetRelid(node->ss.ss_currentRelation), &svr_database, &svr_table);
+
 	/* Connect to the server */
-	if (sqlite3_open("/home/guillaume/toto/test.db", &db)) {
+	if (sqlite3_open(svr_database, &db)) {
 		ereport(ERROR,
 			(errcode(ERRCODE_FDW_OUT_OF_MEMORY),
-			errmsg("Can't open sqlite database: %s", sqlite3_errmsg(db))
+			errmsg("Can't open sqlite database %s: %s", svr_database, sqlite3_errmsg(db))
 			));
 		sqlite3_close(db);
 	}
 
 	/* Build the query */
-	query = (char *)palloc(17);
-	snprintf(query, 17, "SELECT * FROM t1");
+    len = strlen(svr_table) + 15;
+    query = (char *)palloc(len);
+    snprintf(query, len, "SELECT * FROM %s", svr_table);
 
 	/* Stash away the state info we have already */
 	festate = (SQLiteFdwExecutionState *) palloc(sizeof(SQLiteFdwExecutionState));