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SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

Artifact c125622a813325bba1b4999040ddc213773c2290:


# 2011 March 3
#
# 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 implements tests for SQLite library.  The focus of the tests
# in this file a corner-case query planner optimization involving the
# join order of two tables of different sizes.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

ifcapable !stat2 {
  finish_test
  return
}

set testprefix analyze6

proc eqp {sql {db db}} {
  uplevel execsql [list "EXPLAIN QUERY PLAN $sql"] $db
}

do_test analyze6-1.0 {
  db eval {
    CREATE TABLE cat(x INT);
    CREATE UNIQUE INDEX catx ON cat(x);
    /* Give cat 16 unique integers */
    INSERT INTO cat VALUES(1);
    INSERT INTO cat VALUES(2);
    INSERT INTO cat SELECT x+2 FROM cat;
    INSERT INTO cat SELECT x+4 FROM cat;
    INSERT INTO cat SELECT x+8 FROM cat;

    CREATE TABLE ev(y INT);
    CREATE INDEX evy ON ev(y);
    /* ev will hold 32 copies of 16 integers found in cat */
    INSERT INTO ev SELECT x FROM cat;
    INSERT INTO ev SELECT x FROM cat;
    INSERT INTO ev SELECT y FROM ev;
    INSERT INTO ev SELECT y FROM ev;
    INSERT INTO ev SELECT y FROM ev;
    INSERT INTO ev SELECT y FROM ev;
    ANALYZE;
    SELECT count(*) FROM cat;
    SELECT count(*) FROM ev;
  }
} {16 512}

# The lowest cost plan is to scan CAT and for each integer there, do a single
# lookup of the first corresponding entry in EV then read off the equal values
# in EV.  (Prior to the 2011-03-04 enhancement to where.c, this query would
# have used EV for the outer loop instead of CAT - which was about 3x slower.)
#
do_test analyze6-1.1 {
  eqp {SELECT count(*) FROM ev, cat WHERE x=y}
} {0 0 1 {SCAN TABLE cat (~16 rows)} 0 1 0 {SEARCH TABLE ev USING COVERING INDEX evy (y=?) (~32 rows)}}

# The same plan is chosen regardless of the order of the tables in the
# FROM clause.
#
do_test analyze6-1.2 {
  eqp {SELECT count(*) FROM cat, ev WHERE x=y}
} {0 0 0 {SCAN TABLE cat (~16 rows)} 0 1 1 {SEARCH TABLE ev USING COVERING INDEX evy (y=?) (~32 rows)}}


# Ticket [83ea97620bd3101645138b7b0e71c12c5498fe3d] 2011-03-30
# If ANALYZE is run on an empty table, make sure indices are used
# on the table.
#
do_test analyze6-2.1 {
  execsql {
    CREATE TABLE t201(x INTEGER PRIMARY KEY, y UNIQUE, z);
    CREATE INDEX t201z ON t201(z);
    ANALYZE;
  }
  eqp {SELECT * FROM t201 WHERE z=5}
} {0 0 0 {SEARCH TABLE t201 USING INDEX t201z (z=?) (~10 rows)}}
do_test analyze6-2.2 {
  eqp {SELECT * FROM t201 WHERE y=5}
} {0 0 0 {SEARCH TABLE t201 USING INDEX sqlite_autoindex_t201_1 (y=?) (~1 rows)}}
do_test analyze6-2.3 {
  eqp {SELECT * FROM t201 WHERE x=5}
} {0 0 0 {SEARCH TABLE t201 USING INTEGER PRIMARY KEY (rowid=?) (~1 rows)}}
do_test analyze6-2.4 {
  execsql {
    INSERT INTO t201 VALUES(1,2,3);
    ANALYZE t201;
  }
  eqp {SELECT * FROM t201 WHERE z=5}
} {0 0 0 {SEARCH TABLE t201 USING INDEX t201z (z=?) (~10 rows)}}
do_test analyze6-2.5 {
  eqp {SELECT * FROM t201 WHERE y=5}
} {0 0 0 {SEARCH TABLE t201 USING INDEX sqlite_autoindex_t201_1 (y=?) (~1 rows)}}
do_test analyze6-2.6 {
  eqp {SELECT * FROM t201 WHERE x=5}
} {0 0 0 {SEARCH TABLE t201 USING INTEGER PRIMARY KEY (rowid=?) (~1 rows)}}
do_test analyze6-2.7 {
  execsql {
    INSERT INTO t201 VALUES(4,5,7);
    INSERT INTO t201 SELECT x+100, y+100, z+100 FROM t201;
    INSERT INTO t201 SELECT x+200, y+200, z+200 FROM t201;
    INSERT INTO t201 SELECT x+400, y+400, z+400 FROM t201;
    ANALYZE t201;
  }
  eqp {SELECT * FROM t201 WHERE z=5}
} {0 0 0 {SEARCH TABLE t201 USING INDEX t201z (z=?) (~10 rows)}}
do_test analyze6-2.8 {
  eqp {SELECT * FROM t201 WHERE y=5}
} {0 0 0 {SEARCH TABLE t201 USING INDEX sqlite_autoindex_t201_1 (y=?) (~1 rows)}}
do_test analyze6-2.9 {
  eqp {SELECT * FROM t201 WHERE x=5}
} {0 0 0 {SEARCH TABLE t201 USING INTEGER PRIMARY KEY (rowid=?) (~1 rows)}}

finish_test