persistentstorage/sqlite3api/TEST/TclScript/pageropt.test
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     1 # 2007 April 12
       
     2 #
       
     3 # The author disclaims copyright to this source code.  In place of
       
     4 # a legal notice, here is a blessing:
       
     5 #
       
     6 #    May you do good and not evil.
       
     7 #    May you find forgiveness for yourself and forgive others.
       
     8 #    May you share freely, never taking more than you give.
       
     9 #
       
    10 #***********************************************************************
       
    11 # This file implements regression tests for SQLite library.
       
    12 # The focus of the tests in this file are to verify that the
       
    13 # pager optimizations implemented in version 3.3.14 work.
       
    14 #
       
    15 # $Id: pageropt.test,v 1.5 2008/08/20 14:49:25 danielk1977 Exp $
       
    16 
       
    17 set testdir [file dirname $argv0]
       
    18 source $testdir/tester.tcl
       
    19 
       
    20 ifcapable {!pager_pragmas||secure_delete} {
       
    21   finish_test
       
    22   return
       
    23 }
       
    24 
       
    25 # Run the SQL statement supplied by the argument and return
       
    26 # the results.  Prepend four integers to the beginning of the
       
    27 # result which are
       
    28 #
       
    29 #     (1)  The number of page reads from the database
       
    30 #     (2)  The number of page writes to the database
       
    31 #     (3)  The number of page writes to the journal
       
    32 #     (4)  The number of cache pages freed
       
    33 #
       
    34 proc pagercount_sql {sql {db db}} {
       
    35   global sqlite3_pager_readdb_count
       
    36   global sqlite3_pager_writedb_count
       
    37   global sqlite3_pager_writej_count
       
    38   global sqlite3_pager_pgfree_count
       
    39   set sqlite3_pager_readdb_count 0
       
    40   set sqlite3_pager_writedb_count 0
       
    41   set sqlite3_pager_writej_count 0
       
    42   set r [$db eval $sql]
       
    43   set cnt [list $sqlite3_pager_readdb_count \
       
    44                 $sqlite3_pager_writedb_count \
       
    45                 $sqlite3_pager_writej_count ]
       
    46   return [concat $cnt $r]
       
    47 }
       
    48 
       
    49 # Setup the test database
       
    50 #
       
    51 do_test pageropt-1.1 {
       
    52   sqlite3_soft_heap_limit 0
       
    53   execsql {
       
    54     PRAGMA auto_vacuum = OFF;
       
    55     PRAGMA page_size = 1024;
       
    56   }
       
    57   pagercount_sql {
       
    58     CREATE TABLE t1(x);
       
    59   }
       
    60 } {0 2 0}
       
    61 do_test pageropt-1.2 {
       
    62   pagercount_sql {
       
    63     INSERT INTO t1 VALUES(randomblob(5000));
       
    64   }
       
    65 } {0 6 2}
       
    66 
       
    67 # Verify that values remain in cache on for subsequent reads.
       
    68 # We should not have to go back to disk.
       
    69 #
       
    70 do_test pageropt-1.3 {
       
    71   pagercount_sql {
       
    72     SELECT length(x) FROM t1
       
    73   }
       
    74 } {0 0 0 5000}
       
    75 
       
    76 # If another thread reads the database, the original cache
       
    77 # remains valid.
       
    78 #
       
    79 sqlite3 db2 test.db
       
    80 set blobcontent [db2 one {SELECT hex(x) FROM t1}]
       
    81 do_test pageropt-1.4 {
       
    82   pagercount_sql {
       
    83     SELECT hex(x) FROM t1
       
    84   }
       
    85 } [list 0 0 0 $blobcontent]
       
    86 
       
    87 # But if the other thread modifies the database, then the cache
       
    88 # must refill.
       
    89 #
       
    90 do_test pageropt-1.5 {
       
    91   db2 eval {CREATE TABLE t2(y)}
       
    92   pagercount_sql {
       
    93     SELECT hex(x) FROM t1
       
    94   }
       
    95 } [list 6 0 0 $blobcontent]
       
    96 do_test pageropt-1.6 {
       
    97   pagercount_sql {
       
    98     SELECT hex(x) FROM t1
       
    99   }
       
   100 } [list 0 0 0 $blobcontent]
       
   101 
       
   102 # Verify that the last page of an overflow chain is not read from
       
   103 # disk when deleting a row.  The one row of t1(x) has four pages
       
   104 # of overflow.  So deleting that row from t1 should involve reading
       
   105 # the sqlite_master table (1 page) the main page of t1 (1 page) and
       
   106 # the three overflow pages of t1 for a total of 5 pages.
       
   107 #
       
   108 # Pages written are page 1 (for the freelist pointer), the root page
       
   109 # of the table, and one of the overflow chain pointers because it
       
   110 # becomes the trunk of the freelist.  Total 3.
       
   111 #
       
   112 do_test pageropt-2.1 {
       
   113   db close
       
   114   sqlite3 db test.db
       
   115   pagercount_sql {
       
   116     DELETE FROM t1 WHERE rowid=1
       
   117   }
       
   118 } {5 3 3}
       
   119 
       
   120 # When pulling pages off of the freelist, there is no reason
       
   121 # to actually bring in the old content.
       
   122 #
       
   123 do_test pageropt-2.2 {
       
   124   db close
       
   125   sqlite3 db test.db
       
   126   pagercount_sql {
       
   127     INSERT INTO t1 VALUES(randomblob(1500));
       
   128   }
       
   129 } {3 4 3}
       
   130 do_test pageropt-2.3 {
       
   131   pagercount_sql {
       
   132     INSERT INTO t1 VALUES(randomblob(1500));
       
   133   }
       
   134 } {0 4 3}
       
   135 
       
   136 # Note the new optimization that when pulling the very last page off of the
       
   137 # freelist we do not read the content of that page.
       
   138 #
       
   139 do_test pageropt-2.4 {
       
   140   pagercount_sql {
       
   141     INSERT INTO t1 VALUES(randomblob(1500));
       
   142   }
       
   143 } {0 5 3}
       
   144 
       
   145 # Appending a large quantity of data does not involve writing much
       
   146 # to the journal file.
       
   147 #
       
   148 do_test pageropt-3.1 {
       
   149   pagercount_sql {
       
   150     INSERT INTO t2 SELECT * FROM t1;
       
   151   }
       
   152 } {1 7 2}
       
   153 
       
   154 # Once again, we do not need to read the last page of an overflow chain
       
   155 # while deleting.
       
   156 #
       
   157 do_test pageropt-3.2 {
       
   158   pagercount_sql {
       
   159     DROP TABLE t2;
       
   160   }
       
   161 } {0 2 3}
       
   162 do_test pageropt-3.3 {
       
   163   pagercount_sql {
       
   164     DELETE FROM t1;
       
   165   }
       
   166 } {0 3 3}
       
   167 
       
   168 # There are now 11 pages on the freelist.  Move them all into an
       
   169 # overflow chain by inserting a single large record.  Starting from
       
   170 # a cold cache, only page 1, the root page of table t1, and the trunk
       
   171 # of the freelist need to be read (3 pages).  And only those three
       
   172 # pages need to be journalled.  But 13 pages need to be written:
       
   173 # page1, the root page of table t1, and an 11 page overflow chain.
       
   174 #
       
   175 do_test pageropt-4.1 {
       
   176   db close
       
   177   sqlite3 db test.db
       
   178   pagercount_sql {
       
   179     INSERT INTO t1 VALUES(randomblob(11300))
       
   180   }
       
   181 } {3 13 3}
       
   182 
       
   183 # Now we delete that big entries starting from a cold cache and an
       
   184 # empty freelist.  The first 10 of the 11 pages overflow chain have
       
   185 # to be read, together with page1 and the root of the t1 table.  12
       
   186 # reads total.  But only page1, the t1 root, and the trunk of the
       
   187 # freelist need to be journalled and written back.
       
   188 #
       
   189 do_test pageropt-4.2 {
       
   190   db close
       
   191   sqlite3 db test.db
       
   192   pagercount_sql {
       
   193     DELETE FROM t1
       
   194   }
       
   195 } {12 3 3}
       
   196 
       
   197 sqlite3_soft_heap_limit $soft_limit
       
   198 catch {db2 close}
       
   199 finish_test