From 38bb4caa1e3839fbd88468fdad0764e23242480e Mon Sep 17 00:00:00 2001
From: Roman Khabibov <roman.habibov@tarantool.org>
Date: Mon, 29 Jul 2019 18:00:34 +0300
Subject: [PATCH] sql: allow to create view as <WITH> clause
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Allow views to use CTEs, which can be in any (nested) select after
<AS>. Before this patch, during view creation all referenced
spaces were fetched by name from SELECT and their reference
counters were incremented to avoid dangling references. It
occurred in update_view_references(). Obviously, CTE tables
weren't held in space cache, ergo error "space doesn’t exist" was
raised. Add check if a space from FROM is CTE. If it is, don't
increment its reference counter and don't raise the error.
Closes #4149
---
src/box/alter.cc | 10 ++++
src/box/sql.h | 13 ++++++
src/box/sql/select.c | 40 ++++++++++++++++
test/sql-tap/view.test.lua | 94 +++++++++++++++++++++++++++++++++++++-
4 files changed, 156 insertions(+), 1 deletion(-)
diff --git a/src/box/alter.cc b/src/box/alter.cc
index 499df1ca25..bb3686d6ef 100644
--- a/src/box/alter.cc
+++ b/src/box/alter.cc
@@ -1760,6 +1760,16 @@ update_view_references(struct Select *select, int update_value,
const char *space_name = sql_src_list_entry_name(list, i);
if (space_name == NULL)
continue;
+ /*
+ * Views are allowed to contain CTEs. CTE is a
+ * temporary object, created and destroyed at SQL
+ * runtime (it is represented by an ephemeral
+ * table). So, it is absent in space cache and as
+ * a consequence we can't increment its reference
+ * counter. Skip iteration.
+ */
+ if (sql_select_constains_cte(select, space_name))
+ continue;
struct space *space = space_by_name(space_name);
if (space == NULL) {
if (! suppress_error) {
diff --git a/src/box/sql.h b/src/box/sql.h
index 7644051b4f..0fa52fc0bf 100644
--- a/src/box/sql.h
+++ b/src/box/sql.h
@@ -323,6 +323,19 @@ sql_select_delete(struct sql *db, struct Select *select);
struct SrcList *
sql_select_expand_from_tables(struct Select *select);
+/**
+ * Check if @a name matches with at least one of CTE names typed
+ * in <WITH> clauses within @a select except <WITH>s that are
+ * nested within other <WITH>s.
+ *
+ * @param select Select which may contain CTE.
+ * @param name The name of CTE, that may contained.
+ * @retval true Has CTE with @a name.
+ * @retval false Hasn't CTE with @a name.
+*/
+bool
+sql_select_constains_cte(struct Select *select, const char *name);
+
/**
* Temporary getter in order to avoid including sqlInt.h
* in alter.cc.
diff --git a/src/box/sql/select.c b/src/box/sql/select.c
index cdcdbaf2b8..8f93edd169 100644
--- a/src/box/sql/select.c
+++ b/src/box/sql/select.c
@@ -332,6 +332,46 @@ sql_select_expand_from_tables(struct Select *select)
return walker.u.pSrcList;
}
+bool
+sql_select_constains_cte(struct Select *select, const char *name)
+{
+ assert(select != NULL && name != NULL);
+ struct With *with = select->pWith;
+ if (with != NULL) {
+ for (int i = 0; i < with->nCte; i++) {
+ const struct Cte *cte = &with->a[i];
+ /*
+ * Don't use recursive call for
+ * cte->pSelect, because this function is
+ * used during view creation. Consider
+ * the nested <WITH>s query schema:
+ * CREATE VIEW v AS
+ * WITH w AS (
+ * WITH w_nested AS
+ * (...)
+ * SELECT ...)
+ * SELECT ... FROM ...;
+ * The use of CTE "w_nested" after the
+ * external select's <FROM> is disallowed.
+ * So, it is pointless to check <WITH>,
+ * which is nested to other <WITH>.
+ */
+ if (memcmp(name, cte->zName, strlen(name)) == 0)
+ return true;
+ }
+ }
+ struct SrcList *list = select->pSrc;
+ int item_count = sql_src_list_entry_count(list);
+ for (int i = 0; i < item_count; ++i) {
+ if (list->a[i].pSelect != NULL) {
+ if (sql_select_constains_cte(list->a[i].pSelect,
+ name))
+ return true;
+ }
+ }
+ return false;
+}
+
/*
* Given 1 to 3 identifiers preceding the JOIN keyword, determine the
* type of join. Return an integer constant that expresses that type
diff --git a/test/sql-tap/view.test.lua b/test/sql-tap/view.test.lua
index 101f4c3e74..6234f863eb 100755
--- a/test/sql-tap/view.test.lua
+++ b/test/sql-tap/view.test.lua
@@ -1,6 +1,6 @@
#!/usr/bin/env tarantool
test = require("sqltester")
-test:plan(73)
+test:plan(78)
--!./tcltestrunner.lua
-- 2002 February 26
@@ -1233,4 +1233,96 @@ test:do_catchsql_test(
-- </view-23.8>
})
+-- gh-4149: Make sure that VIEW can be created as CTE.
+test:do_execsql_test(
+ "view-24.1",
+ [[
+ CREATE TABLE ts (s1 INT PRIMARY KEY);
+ INSERT INTO ts VALUES (1);
+ ]], {
+ -- <view-24.1>
+ -- </view-24.1>
+ })
+
+test:do_execsql_test(
+ "view-24.2",
+ [[
+ CREATE VIEW v AS WITH w(id) AS (
+ SELECT 1)
+ SELECT * FROM ts, w;
+ SELECT * FROM v;
+ ]], {
+ -- <view-24.2>
+ 1, 1
+ -- </view-24.2>
+ })
+
+test:do_execsql_test(
+ "view-24.3",
+ [[
+ DROP VIEW v;
+ CREATE VIEW v AS WITH RECURSIVE w AS (
+ SELECT s1 FROM ts
+ UNION ALL
+ SELECT s1+1 FROM w WHERE s1 < 4)
+ SELECT * FROM w;
+ SELECT * FROM v;
+ ]], {
+ -- <view-24.3>
+ 1,2,3,4
+ -- </view-24.3>
+ })
+
+test:do_execsql_test(
+ "view-24.4",
+ [[
+ DROP VIEW v;
+ CREATE VIEW v AS SELECT * FROM
+ (SELECT 1),
+ (SELECT 2) JOIN
+ (WITH RECURSIVE w AS (
+ SELECT s1 FROM ts
+ UNION ALL
+ SELECT s1+1 FROM w WHERE s1 < 4)
+ SELECT * FROM w);
+ SELECT * FROM v;
+ ]], {
+ -- <view-24.4>
+ 1,2,1,1,2,2,1,2,3,1,2,4
+ -- </view-24.4>
+ })
+
+test:do_execsql_test(
+ "view-24.5",
+ [[
+ DROP VIEW v;
+ DROP TABLE ts;
+ CREATE VIEW v AS WITH RECURSIVE
+ xaxis(x) AS (
+ VALUES(-2.0)
+ UNION ALL
+ SELECT x+0.5 FROM xaxis WHERE x<1.2),
+ yaxis(y) AS (
+ VALUES(-1.0)
+ UNION ALL
+ SELECT y+0.5 FROM yaxis WHERE y<1.0),
+ m(iter, cx, cy, x, y) AS (
+ SELECT 0, x, y, 0.0, 0.0 FROM xaxis, yaxis
+ UNION ALL
+ SELECT iter+1, cx, cy, x*x-y*y + cx, 2.0*x*y + cy FROM m WHERE (x*x + y*y) < 4.0 AND iter<1
+ ),
+ m2(iter, cx, cy) AS (
+ SELECT max(iter), cx, cy FROM m GROUP BY cx, cy
+ ),
+ a(t) AS (
+ SELECT group_concat( substr('a', 1+least(iter/7,4), 1), '') FROM m2 GROUP BY cy
+ )
+ SELECT group_concat(trim(t),x'0a') FROM a;
+ SELECT * FROM v;
+ ]], {
+ -- <view-24.5>
+ "aaaaaaaa\naaaaaaaa\naaaaaaaa\naaaaaaaa\naaaaaaaa"
+ -- </view-24.5>
+ })
+
test:finish_test()
--
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