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I have a Perl program that we have run successfully every day for almost the past 2 years, but which crashes today with the error message:

FATAL ERR: Can't do PRAGMA cache_size = 1000000: attempt to write a readonly database

The SQLite database in question is readonly, and always has been, and the code has always used PRAGMA cache_size = 1000000 on it immediately after opening its readonly connection.

Setting cache_size is not a write operation, and does not fail if I access the db directly thru the DBI, like this:

$dbh->do("PRAGMA cache_size = 1000000")

However, the code makes SqliteH::db a subclass of DBI::db, then calls this function from the subclass:

$self->SUPER::do("PRAGMA cache_size = 1000000")

and it now dies with "DBD::SQLite::db do failed: attempt to write a readonly database at /local/ifs_projects/prok/function/src/lib/SqliteH.pm line 329."

The code worked with CentOS 5, Perl 5.10.1, DBD::SQLite 1.29, and DBI 1.611. It does not work CentOS 6, Perl 5.16, DBD::SQLite 1.39, and DBI 1.627. I am however mystified that it /did/ work last week on CentOS 6 and Perl 5.16. IT may have upgraded DBD::SQLite or DBI over the weekend.

Please do not change the title to "Suddenly getting error on program that has worked for months" again. That is an unhelpful and nonspecific title.

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TL;DR - 如果事务开启，那么任何命令都会尝试写入事务日志。如果数据库是只读的，则从 dbh 连接标志中删除 AutoCommit=>0 [您也不应该有任何 ->begin_work() 或 INSERT/UPDATE 调用，但这从未在只读数据库上工作:-)] .

事实证明，在更新 SQLite、DBI 和 DBD::SQLite 后，我今天遇到了完全相同的问题（所以我不知道它们中的哪一个导致了问题），但在我的情况下，在一个 select 上（这使得它更莫名其妙）。原来在原来的连接字符串中开启了事务：

my $dbh=DBI->connect('dbi:SQLite:file.db','','',, {PrintError=>1,RaiseError=>1,AutoCommit=>0});

而且，在跟踪代码之后，我注意到它实际上在尝试启动事务时崩溃了。

  DB<4> $dbh->trace(15)
    DBI::db=HASH(0x18b9c38) trace level set to 0x0/15 (DBI @ 0x0/0) in DBI 1.627-ithread (pid 15740)
  DB<5> $sth= $dbh->prepare("SELECT key,value FROM annotation where accession=?")
    ...
  DB<6> $sth->execute('D3FET3')
    -> execute for DBD::SQLite::st (DBI::st=HASH(0x18ba340)~0x18ba178 'D3FET3') thr#10cd010
    sqlite trace: bind into 0x18ba268: 1 => D3FET3 (0) pos 0 at dbdimp.c line 1232
    sqlite trace: executing SELECT key,value FROM annotation where accession=? at dbdimp.c line 660
    sqlite trace: bind 0 type 3 as D3FET3 at dbdimp.c line 677
    sqlite trace: BEGIN TRAN at dbdimp.c line 774
    sqlite error 8 recorded: attempt to write a readonly database at dbdimp.c line 79
      !! ERROR: '8' 'attempt to write a readonly database' (err#1)
      <- execute= ( undef ) [1 items] at (eval 15)[/usr/local/packages/perl-5.16.1/lib/5.16.1/perl5db.pl:646] line 2 via  at -e line 1
    DBD::SQLite::st execute failed: attempt to write a readonly database at (eval 15)[/usr/local/packages/perl-5.16.1/lib/5.16.1/perl5db.pl:646] line 2.
    ...

删除 connect() 调用中的 AutoCommit=>0 标志解决了我的问题。

于 2013-07-22T22:20:28.667 回答