Changeset 27298


Ignore:
Timestamp:
2013-05-06T14:18:28+12:00 (8 years ago)
Author:
jmt12
Message:

Add hidden support for the new experimental multiple reader/writer functionality available in SQLite

File:
1 edited

Legend:

Unmodified
Added
Removed
  • main/trunk/greenstone2/perllib/dbutil/sqlite.pm

    r24190 r27298  
    3737my $db_fast = 0;
    3838
     39# Set to 1 to enable Write Ahead Logging - which is supposed to allow multiple
     40# readers/writers on a SQLite database (incompatible with db_fast). From SQLite
     41# 3.7 onwards, WAL offers limited parallel reader/writer support but is limited
     42# to single computers (doesn't work over networked filesystems). For details
     43# see: http://www.sqlite.org/draft/wal.html [jmt12]
     44my $db_wal = 0;
    3945
    4046# -----------------------------------------------------------------------------
     
    6066  # to the web page first, as part of the web page's headers, thus ruining the web page
    6167  # which causes an Internal Server Error (500). Therefore, we redirect sqlite's output to
    62   # the nul device instead.
     68  # the nul device instead.
     69  # using WAL mode (which also changes the journal) suffers a similar issue [jmt12]
    6370  my $nul_device="";
    64   if(defined $db_fast && $db_fast == 1) {
     71  if($db_fast == 1 || $db_wal == 1) {
    6572    if($ENV{'GSDLOS'} =~ m/windows/) {
    6673        $nul_device=">NUL";
     
    8592    print $infodb_handle "PRAGMA journal_mode=MEMORY;\n";
    8693  }
    87  
     94  # Allow parallel readers/writers by using a Write Ahead Logger
     95  elsif ($db_wal)
     96  {
     97    print $infodb_handle "PRAGMA journal_mode=WAL;\n";
     98  }
     99
    88100  # This is very important for efficiency, otherwise each command will be actioned one at a time
    89101  print $infodb_handle "BEGIN TRANSACTION;\n";
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