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test/selectG.test
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drh
Avoid excess stack usage when a VALUES clause with lots of rows occurs
14 янв 2018, 23:12
14 янв 2018, 23:12
b058d05
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# 2015-01-05 # # The author disclaims copyright to this source code. In place of # a legal notice, here is a blessing: # # May you do good and not evil. # May you find forgiveness for yourself and forgive others. # May you share freely, never taking more than you give. # #*********************************************************************** # # This file verifies that INSERT operations with a very large number of # VALUE terms works and does not hit the SQLITE_LIMIT_COMPOUND_SELECT limit. # set testdir [file dirname $argv0] source $testdir/tester.tcl set testprefix selectG # Do an INSERT with a VALUES clause that contains 100,000 entries. Verify # that this insert happens quickly (in less than 10 seconds). Actually, the # insert will normally happen in less than 0.5 seconds on a workstation, but # we allow plenty of overhead for slower machines. The speed test checks # for an O(N*N) inefficiency that was once in the code and that would make # the insert run for over a minute. # do_test 100 { set sql "CREATE TABLE t1(x);\nINSERT INTO t1(x) VALUES" for {set i 1} {$i<100000} {incr i} { append sql "($i)," } append sql "($i);" set microsec [lindex [time {db eval $sql}] 0] db eval { SELECT count(x), sum(x), avg(x), $microsec<10000000 FROM t1; } } {100000 5000050000 50000.5 1} # 2018-01-14. A 100K-entry VALUES clause within a scalar expression does # not cause processor stack overflow. # do_test 110 { set sql "SELECT (VALUES" for {set i 1} {$i<100000} {incr i} { append sql "($i)," } append sql "($i));" db eval $sql } {1} # Only the left-most term of a multi-valued VALUES within a scalar # expression is evaluated. # do_test 120 { set n [llength [split [db eval "explain $sql"] \n]] expr {$n<10} } {1} finish_test