[tarantool-patches] Re: [PATCH] sql: xfer optimization issue
- From: Alexander Turenko <alexander.turenko@xxxxxxxxxxxxx>
- To: Nikita Tatunov <hollow653@xxxxxxxxx>
- Date: Sun, 29 Jul 2018 04:12:51 +0300
Hi!
Please consider my comments and questions below.
WBR, Alexander Turenko.
+ /*
+ * Xfer optimization is unable to correctly insert data
+ * in case there's a conflict action other than
+ * explicit *_ABORT. This is the reason we want to only
+ * run it if the destination table is initially empty.
+ * That block generates code to make that determination.
+ */
+ if (!(onError == ON_CONFLICT_ACTION_ABORT &&
+ !is_err_action_default)) {
Do you mean that:
1. The optimization non-empty table case correctly works only with ABORT
conflict action (default or explicit).
2. The default conflict action can be overwritten on per-column basis, so
'default abort' can really be replace or other conflict action.
If so, your description doesn't give this information.
To more on that, can we check per-column conflict actions instead of check
whether the conflict action default or explicit? This would enable more cases
with non-empty tables for the optimization. And this would look less confusing,
IMHO.
I have one more question on that. It seems that SQLite has this optimization
working with ROLLBACK conflict action. We cannot doing so, because of some
problem? Did this problem described / trackerized somewhere? Or something
changes underhood and makes this impossible? Are we know exact reason or just
observing it does not work?
+#ifdef SQLITE_TEST
+/*
+ * The following global variable is incremented whenever the
+ * transfer optimization is used. This is used for testing
+ * purposes only - to make sure the transfer optimization really
+ * is happening when it is supposed to.
+ */
+int sql_xfer_count = 0;
+#endif
I think it would be good to mention the opcode where the counter is
incremented. You can follow the style in which other counters are
described (they are mostly mention opcodes).
-/* Opcode: RowData P1 P2 * * *
+/* Opcode: RowData P1 P2 * * P5
We can increase the counter on per-operation basis instead of per-row by
adding the flag to OP_OpenWrite. It will save some CPU cycles :)
+#ifdef SQLITE_TEST
+ if ((pOp->p5 & OPFLAG_XFER_OPT) != 0) {
+ pOp->p5 = 0;
+ sql_xfer_count++;
+ }
+#endif
1. Not actual due to 2, but it would be better to use
`pOp->p5 &= ~OPFLAG_XFER_OPT` to drop just that flag.
2. It is counter-intuitive, IMHO, to change operation flags during that
operation. So, said above, vote to move it to OP_OpenWrite.
+local bfr, aftr
+
What do you plan to do with saved letters? :) Really, such abbreviations
just makes reading harder with no gains.
+local function do_xfer_test(test_number, return_code)
+ test_name = string.format("xfer-optimization-1.%d", test_number)
+ test:do_test(
+ test_name,
+ function()
+ return {aftr - bfr}
+ end, {
+ -- <test_name>
+ return_code
+ -- <test_name>
+ })
+end
That code can be written simpler (consider tap module documentation):
test:is(after - before, exp, test_name)
I suggest to create wrappers like so (I didn't test it):
local function do_xfer_test(test_func, test, test_name, func, exp, opts)
local opts = opts or {}
local exp_xfer_count = opts.exp_xfer_count
local before = box.sql.debug().sql_xfer_count
local ok = test_func(test, test_name, func, exp)
local after = box.sql.debug().sql_xfer_count
if exp_xfer_count ~= nil then
ok = ok and test:is(after - before, exp_xfer_count, test_name ..
'_xfer_count')
end
return ok
end
test.do_execsql_xfer_test = function(test, test_name, func, exp, opts)
return do_xfer_test(test.do_execsql_test, test, test_name, func, exp, opts)
end
test.do_catchsql_xfer_test = function(test, test_name, func, exp, opts)
return do_xfer_test(test.do_catchsql_test, test, test_name, func, exp, opts)
end
And use it like so:
test:do_catchsql_xfer_test(
"xfer-optimization-1.1",
[[
CREATE TABLE t1(a INTEGER PRIMARY KEY, b INTEGER UNIQUE);
INSERT INTO t1 VALUES (1, 1), (2, 2), (3, 3);
CREATE TABLE t2(a INTEGER PRIMARY KEY, b INTEGER UNIQUE);
INSERT INTO t2 SELECT * FROM t1;
]], {
-- <xfer-optimization-1.1>
0
-- <xfer-optimization-1.1>
}), {
exp_xfer_count = 1
}
)
By the way, you can revive xfer cases in test/sql-tap/with2.test.lua. Or drop
it if your new test includes all related cases from with2.
On Fri, Jul 20, 2018 at 07:58:48PM +0300, Nikita Tatunov wrote:
Ooops. Thank you! fixed it and pushed.
пт, 20 июл. 2018 г. в 19:43, n.pettik <[1]korablev@xxxxxxxxxxxxx>:
LGTM.
diff --git a/src/box/sql/insert.c b/src/box/sql/insert.c
index 3c3bf37..4f52fa5 100644
--- a/src/box/sql/insert.c
+++ b/src/box/sql/insert.c
@@ -1869,7 +1869,7 @@ xferOptimization(Parse * pParse, /* Parser
context */
* table (tab1) is initially empty.
*/
- /* The Vdbe we're building*/
+ /* The Vdbe struct we're building. */
You misunderstood me. What I mean is:
struct Vibe *v = …;
Vdbe *v = sqlite3GetVdbe(pParse);
References
1. mailto:korablev@xxxxxxxxxxxxx
Other related posts:
