Hello Alvaro,
11.05.2020 06:42, Alvaro Herrera wrote:
> (Strangely, I was just thinking about these branches of mine as I
> closed my week last Friday...)
>
> On 2020-May-10, Alexander Lakhin wrote:
>
>> So if we want to make the coverage reports more precise, I see the three
>> ways:
>> 1. Change the stop mode in teardown_node to fast (probably only when
>> configured with --enable-coverage);
>> 2. Explicitly stop nodes in TAP tests (where it's important) -- seems
>> too tedious and troublesome;
>> 3. Explicitly call __gcov_flush in SIGQUIT handler (quickdie)?
> I tried your idea 3 a long time ago and my experiments didn't show an
> increase in coverage [1]. But I like this idea the best, and maybe I
> did something wrong. Attached is the patch I had (on top of
> fc115d0f9fc6), but I don't know if it still applies.
Thanks for the reference to that discussion and your patch.
As I see the issue with that patch is that quickdie() is not the only
SIGQUIT handler. When a backend is interrupted with SIGQUIT, it's
exiting in SignalHandlerForCrashExit().
In fact if I only add __gcov_flush() in SignalHandlerForCrashExit(), it
raises test coverage for `make check -C src/test/recovery/` from
106198 lines/6319 functions
to
106420 lines/6328 functions
It's not yet clear to me what happens when __gcov_flush() called inside
__gcov_flush().
The test coverage changes to:
108432 lines/5417 functions
(number of function calls decreased)
And for example in coverage/src/backend/utils/cache/catcache.c.gcov.html
I see
147 8 : int2eqfast(Datum a, Datum b)
...
153 0 : int2hashfast(Datum datum)
but without __gcov_flush in quickdie() we have:
147 78038 : int2eqfast(Datum a, Datum b)
...
153 255470 : int2hashfast(Datum datum)
So it needs more investigation.
But I can confirm that calling __gcov_flush() in
SignalHandlerForCrashExit() really improves a code coverage report.
I tried to develop a test to elevate a coverage for gist:
https://coverage.postgresql.org/src/backend/access/gist/gistxlog.c.gcov.html
(Please look at the attached test if it could be interesting.)
and came to this issue with a coverage. I tried to play with
GCOV_PREFIX, but without luck.
Yesterday I found the more recent discussion:
https://www.postgresql.org/message-id/flat/44ecae53-9861-71b7-1d43-4658acc52519%402ndquadrant.com#d02e2e61212831fbceadf290637913a0
(where probably the same problem came out).
Finally I've managed to get an expected coverage when I performed
$node_standby->stop() (but __gcov_flush() in SignalHandlerForCrashExit()
helps too).
Best regards,
Alexander
diff --git a/src/test/recovery/t/021_indexes.pl b/src/test/recovery/t/021_indexes.pl
new file mode 100644
index 0000000000..902133d55a
--- /dev/null
+++ b/src/test/recovery/t/021_indexes.pl
@@ -0,0 +1,102 @@
+# Test testing indexes replication
+use strict;
+use warnings;
+use PostgresNode;
+use TestLib;
+use Test::More tests => 1;
+
+# Initialize master node
+my $node_master = get_new_node('master');
+$node_master->init(allows_streaming => 1);
+$node_master->start;
+
+# Add a table for gist index check
+$node_master->safe_psql('postgres',
+ qq{
+create table gist_point_tbl(id int, p point);
+insert into gist_point_tbl(id, p)
+ select g, point(g*10, g*10) from generate_series(10000, 11000) g;
+create index gist_pointidx on gist_point_tbl using gist(p);});
+
+# Take backup
+my $backup_name = 'my_backup';
+$node_master->backup($backup_name);
+
+# Create streaming standby from backup
+my $node_standby = get_new_node('standby');
+$node_standby->init_from_backup($node_master, $backup_name,
+ has_streaming => 1);
+$node_standby->start;
+
+$node_master->safe_psql('postgres', qq{
+create temp table gist_point_tbl_t(id int, p point);
+create index gist_pointidx_t on gist_point_tbl_t using gist(p);
+insert into gist_point_tbl_t(id, p)
+ select g, point(g*10, g*10) from generate_series(1, 1000) g;
+set enable_seqscan=off;
+set enable_bitmapscan=off;
+explain (costs off)
+select p from gist_point_tbl_t where p <@ box(point(0,0), point(100, 100));
+});
+
+$node_master->safe_psql('postgres', qq{
+create unlogged table gist_point_tbl_u(id int, p point);
+create index gist_pointidx_u on gist_point_tbl_u using gist(p);
+insert into gist_point_tbl_u(id, p)
+ select g, point(g*10, g*10) from generate_series(1, 1000) g;
+set enable_seqscan=off;
+set enable_bitmapscan=off;
+explain (costs off)
+select p from gist_point_tbl_u where p <@ box(point(0,0), point(100, 100));
+});
+
+$node_master->safe_psql('postgres', qq{
+insert into gist_point_tbl (id, p)
+ select g, point(g*10, g*10) from generate_series(1, 1000) g;});
+
+$node_master->safe_psql('postgres', "delete from gist_point_tbl where id < 500");
+
+$node_master->safe_psql('postgres', qq{
+create table test as (select x, box(point(x, x),point(x, x))
+ from generate_series(1,4000000) as x);
+
+create index test_idx on test using gist (box);
+
+set enable_seqscan TO false;
+set enable_bitmapscan TO false;
+
+delete from test where box && box(point(0,0), point(100000,100000));
+
+-- This query invokes gistkillitems()
+select count(box) from test where box && box(point(0,0), point(100000,100000));
+});
+
+$node_master->safe_psql('postgres', qq{
+insert into test
+ select x, box(point(x, x),point(x*3, x*3))
+ from generate_series(1,200000) as x;});
+
+$node_master->safe_psql('postgres', qq{
+update test set box = box where x<2000000; vacuum test;});
+$node_master->safe_psql('postgres', qq{
+delete from test where x<1000000; vacuum test;});
+$node_master->safe_psql('postgres', qq{
+insert into test
+ select x, box(point(x, x),point(x, x))
+ from generate_series(1,1000000) as x;});
+
+$node_master->safe_psql('postgres', qq{
+insert into gist_point_tbl (id, p)
+ select g, point(g*5, g*5) from generate_series(1, 10000) g;});
+
+$node_master->wait_for_catchup($node_standby, 'replay');
+
+my $result = $node_standby->safe_psql('postgres', qq{
+set enable_seqscan=off;
+set enable_bitmapscan=off;
+explain (costs off)
+select p from gist_point_tbl where p <@ box(point(0,0), point(100, 100));});
+ok($result =~ /^Index Only Scan using gist_pointidx/, "gist index used on a standby");
+
+#$node_standby->stop();
+#$node_master->stop();
