Re: [sqlite] Strange behavior with wal_checkpoint PRAGMA
On 02/14/2018 09:13 PM, Joshua Watt wrote: Hello, I observed the following behavior when using the wal_checkpoint PRAGMA in TRUNCATE mode: SQLite version 3.22.0 2018-01-22 18:45:57 Enter ".help" for usage hints. Connected to a transient in-memory database. Use ".open FILENAME" to reopen on a persistent database. sqlite> .open test.db sqlite> PRAGMA journal_mode = WAL; wal sqlite> create table test ( key INTEGER PRIMARY KEY, val INTEGER ); sqlite> insert into test values ( 5, 6 ); sqlite> insert into test values ( 6, 6 ); sqlite> PRAGMA wal_checkpoint(TRUNCATE); 0|0|0 According to the documentation, the second and third values should correspond to the number of pages in the write-ahead log and the number of pages that have been moved back to the database file. This works as expected in the other modes, but in TRUNCATE mode the second and third return values are always zero. The reasoning is that the wal file has been truncated. It therefore contains 0 modified pages, 0 of which have already been checkpointed to the database file. Dan. I believe this is because walCheckpoint() triggers a call to walRestartHdr() if the mode is SQLITE_CHEKPOINT_TRUNCATE. Once walCheckpoint() returns, sqlite3WalCheckpoint() attempts to extract the values from the already restarted wal header. Has anyone else expirenced this issue? Thanks, Joshua Watt ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Strange behavior with wal_checkpoint PRAGMA
On Wed, 2018-02-14 at 08:13 -0600, Joshua Watt wrote: > Hello, > > I observed the following behavior when using the wal_checkpoint > PRAGMA > in TRUNCATE mode: > > SQLite version 3.22.0 2018-01-22 18:45:57 > Enter ".help" for usage hints. > Connected to a transient in-memory database. > Use ".open FILENAME" to reopen on a persistent database. > sqlite> .open test.db > sqlite> PRAGMA journal_mode = WAL; > wal > sqlite> create table test ( key INTEGER PRIMARY KEY, val INTEGER ); > sqlite> insert into test values ( 5, 6 ); > sqlite> insert into test values ( 6, 6 ); > sqlite> PRAGMA wal_checkpoint(TRUNCATE); > 0|0|0 > > According to the documentation, the second and third values should > correspond to the number of pages in the write-ahead log and the > number > of pages that have been moved back to the database file. This works > as > expected in the other modes, but in TRUNCATE mode the second and > third > return values are always zero. > > I believe this is because walCheckpoint() triggers a call to > walRestartHdr() if the mode is SQLITE_CHEKPOINT_TRUNCATE. Once > walCheckpoint() returns, sqlite3WalCheckpoint() attempts to extract > the > values from the already restarted wal header. > > Has anyone else expirenced this issue? Ping? > > Thanks, > Joshua Watt ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
[sqlite] Strange behavior with wal_checkpoint PRAGMA
Hello, I observed the following behavior when using the wal_checkpoint PRAGMA in TRUNCATE mode: SQLite version 3.22.0 2018-01-22 18:45:57 Enter ".help" for usage hints. Connected to a transient in-memory database. Use ".open FILENAME" to reopen on a persistent database. sqlite> .open test.db sqlite> PRAGMA journal_mode = WAL; wal sqlite> create table test ( key INTEGER PRIMARY KEY, val INTEGER ); sqlite> insert into test values ( 5, 6 ); sqlite> insert into test values ( 6, 6 ); sqlite> PRAGMA wal_checkpoint(TRUNCATE); 0|0|0 According to the documentation, the second and third values should correspond to the number of pages in the write-ahead log and the number of pages that have been moved back to the database file. This works as expected in the other modes, but in TRUNCATE mode the second and third return values are always zero. I believe this is because walCheckpoint() triggers a call to walRestartHdr() if the mode is SQLITE_CHEKPOINT_TRUNCATE. Once walCheckpoint() returns, sqlite3WalCheckpoint() attempts to extract the values from the already restarted wal header. Has anyone else expirenced this issue? Thanks, Joshua Watt ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users