notmuch/lib/database-private.h, branch debian/0.22-1

lib: Add "lastmod:" queries for filtering by last modification

2015-08-14T16:23:49Z

The implementation is essentially the same as the date range search prior to Jani's fancy date parser.

lib: API to retrieve database revision and UUID

2015-08-13T21:52:51Z

This exposes the committed database revision to library users along with a UUID that can be used to detect when revision numbers are no longer comparable (e.g., because the database has been replaced).

lib: Add per-message last modification tracking

2015-08-13T21:52:51Z

This adds a new document value that stores the revision of the last modification to message metadata, where the revision number increases monotonically with each database commit. An alternative would be to store the wall-clock time of the last modification of each message. In principle this is simpler and has the advantage that any process can determine the current timestamp without support from libnotmuch. However, even assuming a computer's clock never goes backward and ignoring clock skew in networked environments, this has a fatal flaw. Xapian uses (optimistic) snapshot isolation, which means reads can be concurrent with writes. Given this, consider the following time line with a write and two read transactions: write |-X-A--------------| read 1 |---B---| read 2 |---| The write transaction modifies message X and records the wall-clock time of the modification at A. The writer hangs around for a while and later commits its change. Read 1 is concurrent with the write, so it doesn't see the change to X. It does some query and records the wall-clock time of its results at B. Transaction read 2 later starts after the write commits and queries for changes since wall-clock time B (say the reads are performing an incremental backup). Even though read 1 could not see the change to X, read 2 is told (correctly) that X has not changed since B, the time of the last read. In fact, X changed before wall-clock time A, but the change was not visible until *after* wall-clock time B, so read 2 misses the change to X. This is tricky to solve in full-blown snapshot isolation, but because Xapian serializes writes, we can use a simple, monotonically increasing database revision number. Furthermore, maintaining this revision number requires no more IO than a wall-clock time solution because Xapian already maintains statistics on the upper (and lower) bound of each value stream.

lib: add a log function with output to a string in notmuch_database_t

2015-03-28T23:34:15Z

In principle in the future this could do something fancier than asprintf.

Add the NOTMUCH_FEATURE_INDEXED_MIMETYPES database feature

2015-01-24T15:47:47Z

This feature will exist in all newly created databases, but there is no upgrade provided for it. If this flag exists, it indicates that the database was created after the indexed MIME-types feature was added.

lib: Enable ghost messages feature

2014-10-25T17:31:27Z

This fixes the broken thread order test.

lib: Add a ghost messages database feature

2014-10-25T17:25:54Z

This will be implemented over the next several patches. The feature is not yet "enabled" (this does not add it to NOTMUCH_FEATURES_CURRENT).

lib: Database version 3: Introduce fine-grained "features"

2014-08-30T17:42:08Z

Previously, our database schema was versioned by a single number. Each database schema change had to occur "atomically" in Notmuch's development history: before some commit, Notmuch used version N, after that commit, it used version N+1. Hence, each new schema version could introduce only one change, the task of developing a schema change fell on a single person, and it all had to happen and be perfect in a single commit series. This made introducing a new schema version hard. We've seen only two schema changes in the history of Notmuch. This commit introduces database schema version 3; hopefully the last schema version we'll need for a while. With this version, we switch from a single version number to "features": a set of named, independent aspects of the database schema. Features should make backwards compatibility easier. For many things, it should be easy to support databases both with and without a feature, which will allow us to make upgrades optional and will enable "unstable" features that can be developed and tested over time. Features also make forwards compatibility easier. The features recorded in a database include "compatibility flags," which can indicate to an older version of Notmuch when it must support a given feature to open the database for read or for write. This lets us replace the old vague "I don't recognize this version, so something might go wrong, but I promise to try my best" warnings upon opening a database with an unknown version with precise errors. If a database is safe to open for read/write despite unknown features, an older version will know that and issue no message at all. If the database is not safe to open for read/write because of unknown features, an older version will know that, too, and can tell the user exactly which required features it lacks support for.

lib: add date range query support

2012-10-31T19:55:32Z

Add a custom value range processor to enable date and time searches of the form date:since..until, where "since" and "until" are expressions understood by the previously added date/time parser, to restrict the results to messages within a particular time range (based on the Date: header). If "since" or "until" describes date/time at an accuracy of days or less, the values are rounded according to the accuracy, towards past for "since" and towards future for "until". For example, date:november..yesterday would match from the beginning of November until the end of yesterday. Expressions such as date:today..today means since the beginning of today until the end of today. Open-ended ranges are supported (since Xapian 1.2.1), i.e. you can specify date:..until or date:since.. to not limit the start or end date, respectively. CAVEATS: Xapian does not support spaces in range expressions. You can replace the spaces with '_', or (in most cases) '-', or (in some cases) leave the spaces out altogether. Entering date:expr without ".." (for example date:yesterday) will not work as you might expect. You can achieve the expected result by duplicating the expr both sides of ".." (for example date:yesterday..yesterday). Open-ended ranges won't work with pre-1.2.1 Xapian, but they don't produce an error either. Signed-off-by: Jani Nikula

lib: Add support for nested atomic sections.

2011-09-24T01:50:38Z

notmuch_database_t now keeps a nesting count and we only start a transaction or commit for the outermost atomic section. Introduces a new error, NOTMUCH_STATUS_UNBALANCED_ATOMIC.