Daniel Shahaf wrote on Fri, Feb 11, 2022 at 17:39:42 +0000: > Julian Foad wrote on Fri, Feb 11, 2022 at 14:48:28 +0000: > > On 'pristines-on-demand-on-mwf': > ⋮ > > I could do with some help on a SQL test FAIL, when testing against the > > older WC format, in wc-queries-test 3: test_query_expectations(). It > > looks like this: > > > > $ (SRC_DIR=$PWD; cd obj-dir/subversion/tests/libsvn_wc && > > ./wc-queries-test --cleanup > > --config-file=$SRC_DIR/subversion/tests/tests.conf > > --srcdir=$SRC_DIR/subversion/tests/libsvn_wc --wc-format-version=1.14 3 > > | sed "s#$SRC_DIR/##") > > > > subversion/tests/libsvn_wc/wc-queries-test.c:815: > > (apr_err=SVN_ERR_TEST_FAILED) > > svn_tests: E200006: STMT_SELECT_UNREFERENCED_PRISTINES: Uses pristine with > > only 0 index component: ((null)) > > SELECT checksum FROM pristine WHERE refcount = 0 > > subversion/tests/libsvn_wc/wc-queries-test.c:868: > > (apr_err=SVN_ERR_COMPOSED_ERROR) > > svn_tests: E200042: Additional errors: > > subversion/tests/libsvn_wc/wc-queries-test.c:868: > > (apr_err=SVN_ERR_SQLITE_CONSTRAINT) > > svn_tests: E200035: |SCAN TABLE pristine > > FAIL: wc-queries-test 3: test query expectations > > > > The failure is within: > > if (item->search > > && ((item->expression_vars < 2 && is_node_table(item->table)) > > || (item->expression_vars < 1)) > > && !is_result_table(item->table)) > > > > I have taken a look and cannot work out what it means. > > In short, it's checking whether SQLite is using sufficiently many index > columns. STMT_SELECT_UNREFERENCED_PRISTINES does a table scan without > using an index, meaning that query does O(N) work where N is the number > of rows in the table. > > To confirm that, does the test pass if you do «CREATE INDEX foo ON > pristine(refcount)» when creating the SQLite database the test runs on? > > I haven't looked to see whether that's the right fix. That would depend > on whether STMT_SELECT_UNREFERENCED_PRISTINES needs to be performant, > and if it does, on what kind of index would best serve it without > affecting other queries (e.g., INSERTs and DELETEs to that table). > > > Maybe the statement needs to be made to match the exception clause > > "in_list(primary_key_statements, i)", but that's just a semi-educated guess. > > The statements in that list both have «LIMIT 1» on them. That'd be why > they're exempted from the "all queries must use an index" check. > > > > > Excuse brevity.
Looked a bit more. The branch removes STMT_SELECT_UNREFERENCED_PRISTINES from slow_statements[] unconditionally and then creates I_PRISTINE_UNREFERENCED only for f32 wc's. So, just add that statement to that array for f31 wc's. Daniel
