No longer use the "user_catalog_table" storage option.

Now that CreateInitDecodingContext() accepts "need_full_snapshot" argument, we
no longer need to (mis)use the "user_catalog_table" storage option to protect
the table being squeezed against VACUUM.

While getting rid of the "user_catalog_table" option, also removed the code
that deals with "autovacuum_enabled". That wasn't very useful because the
window between disabling the autovacuum and starting the squeeze is usually
very short, so the chance that the setting it avoids concurrent autovacuum is
rather low. And since we never used any other storage options than these two,
the removal of "autovacuum_enabled" allows for further simplification of the
code.

README

@@ -107,8 +107,8 @@ Following is the complete description of table metadata.
   the first processing of the corresponding task failed. Typical reason to
   retry the processing is that table definition got changed while the table
   was being squeezed. If the number of retries is achieved, processing of the
-  table is considered complete. The next task is created as soon as time
-  specified by "task_interval" column of "squeeze.tables" table has elapsed.
+  table is considered complete. The next task is created as soon as the next
+  scheduled time is reached.
 
   The default value of "max_retry" is 0 (i.e. do not retry).
 

expected/squeeze.out

@@ -4,13 +4,7 @@ INSERT INTO a(i, j)
 SELECT x, x
 FROM generate_series(1, 10) AS g(x);
 -- The trivial case.
-SELECT squeeze.set_reloptions('public', 'a', true, false, false);
- set_reloptions 
-----------------
-
-(1 row)
-
-SELECT squeeze.squeeze_table('public', 'a', NULL, NULL, NULL, false, false);
+SELECT squeeze.squeeze_table('public', 'a', NULL, NULL, NULL);
  squeeze_table 
 ---------------
 
@@ -33,14 +27,7 @@ SELECT * FROM a;
 
 -- Clustering by index.
 CREATE INDEX a_i_idx_desc ON a(i DESC);
-SELECT squeeze.set_reloptions('public', 'a', true, false, false);
- set_reloptions 
-----------------
-
-(1 row)
-
-SELECT squeeze.squeeze_table('public', 'a', 'a_i_idx_desc', NULL, NULL, false,
-        false);
+SELECT squeeze.squeeze_table('public', 'a', 'a_i_idx_desc', NULL, NULL);
  squeeze_table 
 ---------------
 
@@ -76,14 +63,7 @@ SELECT reltoastrelid > 0 FROM pg_class WHERE relname='b';
 CREATE TABLE b_copy (LIKE b INCLUDING ALL);
 INSERT INTO b_copy(i, t) SELECT i, t FROM b;
 -- Squeeze.
-SELECT squeeze.set_reloptions('public', 'b', true, false, false);
- set_reloptions 
-----------------
-
-(1 row)
-
-SELECT squeeze.squeeze_table('public', 'b', NULL, NULL, NULL, false,
-        false);
+SELECT squeeze.squeeze_table('public', 'b', NULL, NULL, NULL);
  squeeze_table 
 ---------------
 

pg_squeeze--1.0--1.1.sql

@@ -18,7 +18,13 @@ ALTER TABLE tables ALTER COLUMN schedule SET NOT NULL;
 ALTER TABLE tables DROP COLUMN first_check;
 ALTER TABLE tables DROP COLUMN task_interval;
 
+ALTER TABLE tasks DROP COLUMN autovac;
+ALTER TABLE tasks DROP COLUMN autovac_toast;
 
+-- No longer needed.
+DROP FUNCTION is_autovacuum_enabled(oid);
+
+-- Reflect the changes of both "tables" and "tasks" tables.
 CREATE OR REPLACE FUNCTION add_new_tasks() RETURNS void
 LANGUAGE sql
 AS $$
@@ -47,7 +53,7 @@ AS $$
 		       		u.s <= now()::timetz AND
 				-- ... and it should be one for which no
 				-- task was created yet.
-		       		(u.s > i.last_task_created::timetz OR
+				(u.s > i.last_task_created::timetz OR
 				i.last_task_created ISNULL)
 		)
 		-- Ignore tables for which a task currently exists.
@@ -102,9 +108,145 @@ AS $$
 
 	-- now() is supposed to return the same value as it did in the previous
 	-- query.
-	INSERT INTO squeeze.tasks(table_id, autovac, autovac_toast)
-	SELECT	table_id, squeeze.is_autovacuum_enabled(i.class_id),
-		squeeze.is_autovacuum_enabled(i.class_id_toast)
+	INSERT INTO squeeze.tasks(table_id)
+	SELECT	table_id
 	FROM	squeeze.tables_internal i
 	WHERE	i.last_task_created = now();
 $$;
+
+-- No longer used.
+DROP FUNCTION set_reloptions(name, name, bool, bool, bool);
+
+-- start_next_task() used to call set_reloptions(), so modify it accordingly.
+DROP FUNCTION start_next_task();
+
+CREATE OR REPLACE FUNCTION start_next_task()
+RETURNS void
+LANGUAGE plpgsql
+AS $$
+DECLARE
+	v_tabschema	name;
+	v_tabname	name;
+BEGIN
+	PERFORM
+	FROM squeeze.tasks WHERE active;
+	IF FOUND THEN
+		RETURN;
+	END IF;
+
+	UPDATE	squeeze.tasks t
+	INTO	v_tabschema, v_tabname
+	SET	active = true
+	FROM	squeeze.tables tb
+	WHERE
+		tb.id = t.table_id AND
+		t.id = (SELECT id FROM squeeze.tasks ORDER BY id LIMIT 1)
+	RETURNING tb.tabschema, tb.tabname;
+
+	IF NOT FOUND THEN
+		RETURN;
+	END IF;
+END;
+$$;
+
+
+-- process_current_task() used to call set_reloptions(), so modify it
+-- accordingly.
+DROP FUNCTION process_current_task()
+
+CREATE OR REPLACE FUNCTION process_current_task()
+RETURNS void
+LANGUAGE plpgsql
+AS $$
+DECLARE
+	v_tabschema	name;
+	v_tabname	name;
+	v_cl_index	name;
+	v_rel_tbsp	name;
+	v_ind_tbsps	name[][];
+	v_task_id	int;
+	v_tried		int;
+	v_last_try	bool;
+	v_skip_analyze	bool;
+	v_stmt		text;
+	v_start		timestamptz;
+
+	-- Error info to be logged.
+	v_sql_state	text;
+	v_err_msg	text;
+	v_err_detail	text;
+BEGIN
+	SELECT tb.tabschema, tb.tabname, tb.clustering_index,
+tb.rel_tablespace, tb.ind_tablespaces, t.id, t.tried,
+t.tried >= tb.max_retry, tb.skip_analyze
+	INTO v_tabschema, v_tabname, v_cl_index, v_rel_tbsp, v_ind_tbsps,
+ v_task_id, v_tried, v_last_try, v_skip_analyze
+	FROM squeeze.tasks t, squeeze.tables tb
+	WHERE t.table_id = tb.id AND t.active;
+
+	IF NOT FOUND THEN
+		-- Unexpected deletion by someone else?
+		RETURN;
+	END IF;
+
+	-- Do the actual work.
+	BEGIN
+		v_start := clock_timestamp();
+
+		-- Do the actual processing.
+		--
+		-- If someone dropped the table in between, the exception
+		-- handler below should log the error and cleanup the task.
+		PERFORM squeeze.squeeze_table(v_tabschema, v_tabname,
+ v_cl_index, v_rel_tbsp, v_ind_tbsps);
+
+		INSERT INTO squeeze.log(tabschema, tabname, started, finished)
+		VALUES (v_tabschema, v_tabname, v_start, clock_timestamp());
+
+		PERFORM squeeze.cleanup_task(v_task_id);
+
+		IF NOT v_skip_analyze THEN
+                        -- Analyze the new table, unless user rejects it
+                        -- explicitly.
+			--
+			-- XXX Besides updating planner statistics in general,
+			-- this sets pg_class(relallvisible) to 0, so that
+			-- planner is not too optimistic about this
+			-- figure. The preferrable solution would be to run
+			-- (lazy) VACUUM (with the ANALYZE option) to
+			-- initialize visibility map. However, to make the
+			-- effort worthwile, we shouldn't do it until all
+			-- transactions can see all the changes done by
+			-- squeeze_table() function. What's the most suitable
+			-- way to wait? Asynchronous execution of the VACUUM
+			-- is probably needed in any case.
+                        v_stmt := 'ANALYZE "' || v_tabschema || '"."' ||
+                                v_tabname || '"';
+
+			EXECUTE v_stmt;
+		END IF;
+	EXCEPTION
+		WHEN OTHERS THEN
+			GET STACKED DIAGNOSTICS v_sql_state := RETURNED_SQLSTATE;
+			GET STACKED DIAGNOSTICS v_err_msg := MESSAGE_TEXT;
+			GET STACKED DIAGNOSTICS v_err_detail := PG_EXCEPTION_DETAIL;
+
+			INSERT INTO squeeze.errors(tabschema, tabname,
+				sql_state, err_msg, err_detail)
+			VALUES (v_tabschema, v_tabname, v_sql_state, v_err_msg,
+				v_err_detail);
+
+			-- If the active task failed too many times, delete
+			-- it. start_next_task() will prepare the next one.
+			IF v_last_try THEN
+				PERFORM squeeze.cleanup_task(v_task_id);
+				RETURN;
+			ELSE
+				-- Account for the current attempt.
+				UPDATE squeeze.tasks
+				SET tried = tried + 1
+				WHERE id = v_task_id;
+			END IF;
+	END;
+END;
+$$;

pg_squeeze--1.1.sql

@@ -141,12 +141,7 @@ CREATE TABLE tasks (
 
 	-- How many times did we try to process the task? The common use case
 	-- is that a concurrent DDL broke the processing.
-	tried		int	NOT NULL	DEFAULT 0,
-
-	-- The initial value of "autovacuum_enabled" relation option is stored
-	-- here, and will be restored when we're done.
-	autovac		bool	NOT NULL,
-	autovac_toast	bool	NOT NULL
+	tried		int	NOT NULL	DEFAULT 0
 );
 
 -- Make sure there is at most one active task anytime.
@@ -202,13 +197,6 @@ COMMENT ON COLUMN errors.err_msg IS
 COMMENT ON COLUMN errors.err_detail IS
 	'Detailed error message, if available.';
 
-CREATE FUNCTION is_autovacuum_enabled (
-       relid	oid
-)
-RETURNS bool
-AS 'MODULE_PATHNAME', 'is_autovacuum_enabled'
-LANGUAGE C;
-
 CREATE FUNCTION get_heap_fillfactor(a_relid oid)
 RETURNS int
 AS 'MODULE_PATHNAME', 'get_heap_fillfactor'
@@ -334,9 +322,8 @@ AS $$
 
 	-- now() is supposed to return the same value as it did in the previous
 	-- query.
-	INSERT INTO squeeze.tasks(table_id, autovac, autovac_toast)
-	SELECT	table_id, squeeze.is_autovacuum_enabled(i.class_id),
-		squeeze.is_autovacuum_enabled(i.class_id_toast)
+	INSERT INTO squeeze.tasks(table_id)
+	SELECT	table_id
 	FROM	squeeze.tables_internal i
 	WHERE	i.last_task_created = now();
 $$;
@@ -368,21 +355,6 @@ BEGIN
 	IF NOT FOUND THEN
 		RETURN;
 	END IF;
-
-	-- squeeze_table() function requires the "user_catalog_option" to be
-	-- set, but cannot do it in its own transaction. So do it now.
-	--
-	-- Also disable autovacuum for the table and its TOAST relation. As
-	-- we're gonna "squeeze" the table, VACUUM no longer makes sense.
-	--
-	-- (The join to pg_class and pg_namespace should ensure that we don't
-	-- cause ERROR if someone happened to drop the table w/o unregistering
-	-- it firs.)
-	PERFORM squeeze.set_reloptions(v_tabschema, v_tabname, true, false,
-		false)
-	FROM	pg_class c, pg_namespace n
-	WHERE	c.relname = v_tabname AND c.relnamespace = n.oid AND
-		n.nspname = v_tabschema;
 END;
 $$;
 
@@ -418,8 +390,6 @@ DECLARE
 	v_ind_tbsps	name[][];
 	v_task_id	int;
 	v_tried		int;
-	v_autovac	bool;
-	v_autovac_toast bool;
 	v_last_try	bool;
 	v_skip_analyze	bool;
 	v_stmt		text;
@@ -432,9 +402,9 @@ DECLARE
 BEGIN
 	SELECT tb.tabschema, tb.tabname, tb.clustering_index,
 tb.rel_tablespace, tb.ind_tablespaces, t.id, t.tried,
-t.tried >= tb.max_retry, tb.skip_analyze, t.autovac, t.autovac_toast
+t.tried >= tb.max_retry, tb.skip_analyze
 	INTO v_tabschema, v_tabname, v_cl_index, v_rel_tbsp, v_ind_tbsps,
- v_task_id, v_tried, v_last_try, v_skip_analyze, v_autovac, v_autovac_toast
+ v_task_id, v_tried, v_last_try, v_skip_analyze
 	FROM squeeze.tasks t, squeeze.tables tb
 	WHERE t.table_id = tb.id AND t.active;
 
@@ -452,7 +422,7 @@ t.tried >= tb.max_retry, tb.skip_analyze, t.autovac, t.autovac_toast
 		-- If someone dropped the table in between, the exception
 		-- handler below should log the error and cleanup the task.
 		PERFORM squeeze.squeeze_table(v_tabschema, v_tabname,
- v_cl_index, v_rel_tbsp, v_ind_tbsps, v_autovac, v_autovac_toast);
+ v_cl_index, v_rel_tbsp, v_ind_tbsps);
 
 		INSERT INTO squeeze.log(tabschema, tabname, started, finished)
 		VALUES (v_tabschema, v_tabname, v_start, clock_timestamp());
@@ -494,22 +464,6 @@ t.tried >= tb.max_retry, tb.skip_analyze, t.autovac, t.autovac_toast
 			-- it. start_next_task() will prepare the next one.
 			IF v_last_try THEN
 				PERFORM squeeze.cleanup_task(v_task_id);
-
-				-- squeeze_table() resets the options on
-				-- successful completion, but here we must do
-				-- it explicitly on error.
-				--
-				-- (Join to catalog tables should ensure that
-				-- no ERROR is raised here if the table was
-				-- dropped recently.)
-				PERFORM squeeze.set_reloptions(v_tabschema,
-					v_tabname, false, v_autovac,
-					v_autovac_toast)
-				FROM	pg_class c, pg_namespace n
-				WHERE	c.relname = v_tabname AND
-					c.relnamespace = n.oid AND
-					n.nspname = v_tabschema;
-
 				RETURN;
 			ELSE
 				-- Account for the current attempt.
@@ -521,25 +475,12 @@ t.tried >= tb.max_retry, tb.skip_analyze, t.autovac, t.autovac_toast
 END;
 $$;
 
-CREATE FUNCTION set_reloptions (
-	tabchema	name,
-	tabname		name,
-	user_cat	bool,
-	autovac		bool,
-	autovac_toast	bool
-)
-RETURNS void
-AS 'MODULE_PATHNAME', 'set_reloptions'
-LANGUAGE C;
-
 CREATE FUNCTION squeeze_table(
        tabchema		name,
        tabname		name,
        clustering_index name,
        rel_tablespace 	name,
-       ind_tablespaces	name[][],
-       autovac		bool,
-       autovac_toast	bool)
+       ind_tablespaces	name[][])
 RETURNS void
 AS 'MODULE_PATHNAME', 'squeeze_table'
 LANGUAGE C;