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Update to 1.4.1. From the changelog:
API: * Constructing a Query for a non-reference counted PostingSource object will now try to clone the PostingSource object (as happened in 1.3.4 and earlier). This clone code was removed as part of the changes in 1.3.5 to support optional reference counting of PostingSource objects, but that breaks the case when the PostingSource object is on the stack and goes out of scope before the Query object is used. Issue reported by Till Schäfer and analysed by Daniel Vrátil in a bug report against Akonadi: https://bugs.kde.org/show_bug.cgi?id=363741 * Add BM25PlusWeight class implementing the BM25+ weighting scheme, implemented by Vivek Pal (xapian/xapian#104). * Add PL2PlusWeight class implementing the PL2+ weighting scheme, implemented by Vivek Pal (xapian/xapian#108). * LMWeight: Implement Dir+ weighting scheme as DIRICHLET_PLUS_SMOOTHING. Patch from Vivek Pal. * Add CoordWeight class implementing coordinate matching. This can be useful for specialised uses - e.g. to implement sorting by the number of matching filters. * DLHWeight,DPHWeight,PL2Weight: With these weighting schemes, the formulae can give a negative weight contribution for a term in extreme cases. We used to try to handle this by calculating a per-term lower bound on the contribution and subtracting this from the contribution, but this idea is fundamentally flawed as the total offset it adds to a document depends on what combination of terms that document matches, meaning in general the offset isn't the same for every matching document. So instead we now clamp each term's weight contribution to be >= 0. * TfIdfWeight: Always scale term weight by wqf - this seems the logical approach as it matches the weighting we'd get if we weighted every non-unique term in the query, as well as being explicit in the Piv+ formula. * Fix OP_SCALE_WEIGHT to work with all weighting schemes - previously it was ignored when using PL2Weight and LMWeight. * PL2Weight: Greatly improve upper bound on weight: + Split the weight equation into two parts and maximise each separately as that gives an easily solvable problem, and in common cases the maximum is at the same value of wdfn for both parts. In a simple test, the upper bounds are now just over double the highest weight actually achieved - previously they were several hundred times. This approach was suggested by Aarsh Shah in: xapian/xapian#48 + Improve upper bound on normalised wdf (wdfn) - when wdf_upper_bound > doclength_lower_bound, we get a tighter bound by evaluating at wdf=wdf_upper_bound. In a simple test, this reduces the upper bound on wdfn by 36-64%, and the upper bound on the weight by 9-33%. * PL2Weight: Fix calculation of upper_bound when P2>0. P2 is typically negative, but for a very common term it can be positive and then we should use wdfn_lower not wdfn_upper to adjust P_max. * Weight::unserialise(): Check serialised form is empty when unserialising parameter-free schemes BoolWeight, DLHWeight and DPHWeight. * TermGenerator::set_stopper_strategy(): New method to control how the Stopper object is used. Patch from Arnav Jain. * QueryParser: Fix handling of CJK query over multiple prefixes. Previously all the n-gram terms were AND-ed together - now we AND together for each prefix, then OR the results. Fixes #719, reported by Aaron Li. * Add Database::get_revision() method which provides access to the database revision number for chert and glass, intended for use by xapiand. Marked as experimental, so we don't have to go through the usual deprecation cycle if this proves not to be the approach we want to take. Fixes #709, reported by German M. Bravo. * Mark RangeProcessor constructor as `explicit`. * Update to Unicode 9.0.0. * Reimplement ESet and ESetIterator as we did for MSet and MSetIterator in 1.3.5. ESetIterator internally now counts down to the end of the ESet, so the end test is now against 0, rather than against eset.size(). And more of the trivial methods are now inlined, which reduces the number of relocations needed to load the library, and should give faster code which is a very similar size to before. * MSetIterator and ESetIterator are now STL-compatible random_access_iterators (previously they were only bidirectional_iterators). * TfIdfWeight: Support freq and squared IDF normalisations. Patch from Vivek Pal. * New Xapian::Query::OP_INVALID to provide an "invalid" query object. * Reject OP_NEAR/OP_PHRASE with non-leaf subqueries early to avoid a potential segmentation fault if the non-leaf subquery decayed at just the wrong moment. See TritonDataCenter#508. * Reduce positional queries with a MatchAll or PostingSource subquery to MatchNothing (since these subqueries have no positional information, so the query can't match). * Deprecate ValueRangeProcessor and introduce new RangeProcessor class as a replacement. RangeProcessor()::operator()() method returns Xapian::Query, so a range can expand to any query. OP_INVALID is used to signal that a range is not recognised. Fixes #663. * Combining of ranges over the same quantity with OP_OR is now handled by an explicit "grouping" parameter, with a sensible default which works for value range queries. Boolean term prefixes and FieldProcessor now support "grouping" too, so ranges and other filters can now be grouped together. * Formally deprecate WritableDatabase::flush(). The replacement commit() method was added in 1.1.0, so code can be switched to use this and still work with 1.2.x. * Fix handling of a self-initialised PIMPL object (e.g. Xapian::Query q(q);). Previously the uninitialised pointer was copied to itself, resulting in undefined behaviour when the object was used to destroyed. This isn't something you'd see in normal code, but it's a cheap check which can probably be optimised away by the compiler (GCC 6 does). * The Snipper class has been replaced with a new MSet::snippet() method. The implementation has also been redone - the existing implementation was slower than ideal, and didn't directly consider the query so would sometimes selects a snippet which doesn't contain any of the query terms (which users quite reasonably found surprising). The new implementation is faster, will always prefer snippets containing query terms, and also understands exact phrases and wildcards. Fixes TritonDataCenter#211. * Add optional reference counting support for ErrorHandler, ExpandDecider, KeyMaker, PostingSource, Stopper and TermGenerator. Fixes TritonDataCenter#186, reported by Richard Boulton. (ErrorHandler's reference counting isn't actually used anywhere in xapian-core currently, but means we can hook it up in 1.4.x if ticket TritonDataCenter#3 gets addressed). * Deprecate public member variables of PostingSource. The new getters and/or setters added in 1.2.23 and 1.3.5 are preferred. Fixes TritonDataCenter#499, reported by Joost Cassee. * Reimplement MSet and MSetIterator. MSetIterator internally now counts down to the end of the MSet, so the end test is now against 0, rather than against mset.size(). And more of the trivial methods are now inlined, which reduces the number of relocations needed to load the library, and should give faster code which is a very similar size to before. * Only issue prefetch hints for documents if MSet::fetch() is called. It's not useful to send the prefetch hint right before the actual read, which was happening since the implementation of prefetch hints in 1.3.4. Fixes #671, reported by Will Greenberg. * Fix OP_ELITE_SET selection in multi-database case - we were selecting different sets for each subdatabase, but removing the special case check for termfreq_max == 0 solves that. * Remove "experimental" marker from FieldProcessor, since we're happy with the API as-is. Reported by David Bremner on xapian-discuss. * Remove "experimental" marker from Database::check(). We've not had any negative feedback on the current API. * Databse::check() now checks that doccount <= last_docid. * Database::compact() on a WritableDatabase with uncommitted changes could produce a corrupted output. We now throw Xapian::InvalidOperationError in this case, with a message suggesting you either commit() or open the database from disk to compact from. Reported by Will Greenberg on #xapian-discuss * Add Arabic stemmer. Patch from Assem Chelli in xapian/xapian#45 * Improve the Arabic stopword list. Patch from Assem Chelli. * Make functions defined in xapian/iterator.h 'inline'. * Don't force the user to specify the metric in the geospatial API - GreatCircleMetric is probably what most users will want, so a sensible default. * Xapian::DBCHECK_SHOW_BITMAP: This was added in 1.3.0 (so has never been in a stable release) and was superseded by Xapian::DBCHECK_SHOW_FREELIST in 1.3.2, so just remove it. * Make setting an ErrorHandler a no-op - this feature is deprecated and we're not aware of anyone using it. We're hoping to rework ErrorHandler in 1.4.x, which will be simpler without having to support the current behaviour as well as the new. See TritonDataCenter#3. * Update to Unicode 8.0.0. Fixes #680. * Overhaul database compaction API. Add a Xapian::Database::compact() method, with the Database object specifying the source database(s). Xapian::Compactor is now just a functor to use if you want to control progress reporting and/or the merging of user metadata. The existing API has been reimplemented using the new one, but is marked as deprecated. * Add support for a default value when sorting. Fixes TritonDataCenter#452, patch from Richard Boulton. * Make all functor objects non-copyable. Previously some were, some weren't, but it's hard to correctly make use of this ability. Fixes #681. * Fix use after free with WILDCARD_LIMIT_MOST_FREQUENT. If we tried to open a postlist after processing such a wildcard, the postlist hint could be pointing to a PostList object which had been deleted. Fixes #696, reported by coventry. * Add support for optional reference counting of MatchSpy objects. * Improve Document::get_description() - the output is now always valid UTF-8, doesn't contain implementation details like "Document::Internal", and more clearly reports if the document is linked to a database. * Remove XAPIAN_CONST_FUNCTION marker from sortable_serialise_() helper, as it writes to the passed in buffer, so it isn't const or pure. Fixes decvalwtsource2 testcase failure when compiled with clang. * Make PostingSource::set_maxweight() public - it's hard to wrap for the bindings as a protected method. Fixes TritonDataCenter#498, reported by Richard Boulton. * Database: + Add new flag Xapian::DB_RETRY_LOCK which allows opening a database for writing to wait until it can get a write lock. (Fixes TritonDataCenter#275, reported by Richard Boulton). + Fix Database::get_doclength_lower_bound() over multiple databases when some are empty or consist only of zero-length documents. Previously this would report a lower bound of zero, now it reports the same lowest bound as a single database containing all the same documents. + Database::check(): When checking a single table, handle the ".glass" extension on glass database tables, and use the extension to guide the decision of which backend the table is from. * Query: + Add new OP_WILDCARD query operator, which expands wildcards lazily, so now we create the PostList tree for a wildcard directly, rather than creating an intermediate Query tree. OP_WILDCARD offers a choice of ways to limit wildcard expansion (no limit, throw an exception, use the first N by term name, or use the most frequent N). (See tickets TritonDataCenter#48 and #608). * QueryParser: + Add new set_max_expansion() method which provides access to OP_WILDCARD's choice of ways to limit expansion and can set limits for partial terms as well as for wildcards. Partial terms now default to the 100 most frequent matching terms. (Completes #608, reported by boomboo). + Deprecate set_max_wildcard_expansion() in favour of set_max_expansion(). * Add support for optional reference counting of FieldProcessor and ValueRangeProcessor objects. * Update Unicode character database to Unicode 7.0.0. * New Xapian::Snipper class from Mihai Bivol's GSOC 2012 project. (mostly fixes TritonDataCenter#211) * Fix all get_description() methods to always return UTF-8 text. (fixes #620) * Database::check(): + Alter to take its "out" parameter as a pointer to std::ostream instead of a reference, and make passing NULL mean "do not produce output", and make the second and third parameters optional, defaulting to a quiet check. + Escape invalid UTF-8 data in keys and tags reported by xapian-check, using the same code we use to clean up strings returned by get_description() methods. + Correct failure message which talks above the root block when it's actually testing a leaf key. + Rename DBCHECK_SHOW_BITMAP to DBCHECK_SHOW_FREELIST (old name still provided for now, but flagged as deprecated - DBCHECK_SHOW_BITMAP was new in 1.3.0, so will likely be removed before 1.4.0). * Methods and functions which take a string to unserialise now consistently call that parameter "serialised". * Weight: Make number of distinct terms indexing each document and the collection frequency of the term available to subclasses. Patch from Gaurav Arora's Language Modelling branch. * WritableDatabase: Add support for multiple subdatabases, and support opening a stub database containing multiple subdatabases as a WritableDatabase. * WritableDatabase can now be constructed from just a pathname (defaulting to opening the database with DB_CREATE_OR_OPEN). * WritableDatabase: Add flags which can be bitwise OR-ed into the second argument when constructing: + Xapian::DB_NO_SYNC: to disable use of fsync, etc + Xapian::DB_DANGEROUS: to enable in-place updates + Xapian::DB_BACKEND_CHERT: if creating, create a chert database + Xapian::DB_BACKEND_GLASS: if creating, create a glass database + Xapian::DB_NO_TERMLIST: create a database without a termlist (see TritonDataCenter#181) + Xapian::DB_FULL_SYNC flag - if this is set for a database, we use the Mac OS X F_FULL_SYNC instead of fdatasync()/fsync()/etc on the version file when committing. * Database: Add optional flags argument to constructor - the following can be bitwise OR-ed into it: + Xapian::DB_BACKEND_CHERT (only open a chert database) + Xapian::DB_BACKEND_GLASS (only open a glass database) + Xapian::DB_BACKEND_STUB (only open a stub database) * Xapian::Auto::open_stub() and Xapian::Chert::open() are now deprecated in favour of these new flags. * Add LMWeight class, which implements the Unigram Language Modelling weighting scheme. Patch from Gaurav Arora. * Add implementations of a number of DfR weighting schemes (BB2, DLH, DPH, IfB2, IneB2, InL2, PL2). Patches from Aarsh Shah. * Add support for the Bo1 query expansion scheme. Patch from Aarsh Shah. * Add Enquire::set_time_limit() method which sets a timelimit after which check_at_least will be disabled. * Database: Trying to perform operations on a database with no subdatabases now throws InvalidOperationError not DocNotFoundError. * Query: Implement new OP_MAX query operator, which returns the maximum weight of any of its subqueries. (see TritonDataCenter#360) * Query: Add methods to allow introspection on Query objects - currently you can read the leaf type/operator, how many subqueries there are, and get a particular subquery. For a query which is a term, Query::get_terms_begin() allows you to get the term. (see TritonDataCenter#159) * Query: Only simplify OP_SYNONYM with a single subquery if that subquery is a term or MatchAll. * Avoid two vector copies when storing term positions in most common cases. * Reimplement version functions to use a single function in libxapian which returns a pointer to a static const struct containing the version information, with inline wrappers in the API header which call this. This means we only need one relocation instead of 4, reducing library load time a little. * Make TermGenerator flags an anonymous enum, and typedef TermGenerator::flags to int for backward compatibility with existing user code which uses it. * Stem: Fix incorrect Unicode codepoints for o-double-acute and u-double-acute in the Hungarian Snowball stemmer. Reported by Tom Lane to snowball-discuss. * Stem: Add an early english stemmer. * Provide the stopword lists from Snowball plus an Arabic one, installed in ${prefix}/share/xapian-core/stopwords/. Patch from Assem Chelli, fixes TritonDataCenter#269. * Improve check for direct inclusion of Xapian subheaders in user code to catch more cases. * Add simple API to help with creating language-idiomatic iterator wrappers in <xapian/iterator.h>. * Give an compilation error if user code tries to include API headers other than xapian.h directly - these other headers are an internal implementation detail, but experience has shown that some people try to include them directly. Please just use '#include <xapian.h>' instead. * Update Unicode character database to Unicode 6.2.0. * Add FieldProcessor class (ticket#128) - currently marked as an experimental API while we sort out how best to sort out exactly how it interacts with other QueryParser features. * Add implementation of several TF-IDF weighting schemes via a new TfIdfWeight class. * Add ExpandDeciderFilterPrefix class which only return terms with a particular prefix. (fixes TritonDataCenter#467) * QueryParser: Adjust handling of Unicode opening/closing double quotes - if a quoted boolean term was started with ASCII double quote, then only ASCII double quote can end it, as otherwise it's impossible to quote a term containing Unicode double quotes. * Database::check(): If the database can't be opened, don't emit a bogus warning about there being too many documents to cross-check doclens. * TradWeight,BM25Weight: Throw SerialisationError instead of NetworkError if unserialise() fails. * QueryParser: Change the default stemming strategy to STEM_SOME, to eliminate the API gotcha that setting a stemmer is ignored until you also set a strategy. * Deprecate Xapian::ErrorHandler. (ticket#3) * Stem: Generate a compact and efficient table to decode language names. This is both faster and smaller than the approach we were using, with the added benefit that the table is auto-generated. * xapian.h: + Add check for Qt headers being included before us and defining 'slots' as a macro - if they are, give a clear error advising how to work around this (previously compilation would fail with a confusing error). + Add a similar check for Wt headers which also define 'slots' as a macro by default. * Update Unicode character database to Unicode 6.1.0. (ticket#497) * TermIterator returned by Enquire::get_matching_terms_begin(), Query::get_terms_begin(), Database::synonyms_begin(), QueryParser::stoplist_begin(), and QueryParser::unstem_begin() now stores the list of terms to iterate much more compactly. * QueryParser: + Allow Unicode curly double quote characters to start and/or end phrases. + The set_default_op() method will now reject operators which don't make sense to set. The operators which are allowed are now explicitly documented in the API docs. * Query: The internals have been completely reimplemented (ticket#280). The notable changes are: + Query objects are smaller and should be faster. + More readable format for Query::get_description(). + More compact serialisation format for Query objects. + Query operators are no longer flattened as you build up a tree (but the query optimiser still combines groups of the same operator). This means that Query objects are truly immutable, and so we don't need to copy Query objects when composing them. This should also fix a few O(n*n) cases when building up an n-way query pair-wise. (ticket#273) + The Query optimiser can do a few extra optimisations. * There's now explicit support for geospatial search (this API is currently marked as experimental). (ticket#481) * There's now an API (currently experimental) for checking the integrity of databases (partly addresses ticket#238). * Database::reopen() now returns true if the database may have been reopened (previously it returned void). (ticket#548) * Deprecate Xapian::timeout in favour of POSIX type useconds_t. * Deprecate Xapian::percent and use int instead in the API and our own code. * Deprecate Xapian::weight typedef in favour of just using double and change all uses in the API and our own code. (ticket#560) * Rearrange members of Xapian::Error to reduce its size (from 48 to 40 bytes on x86-64 Linux). * Assignment operators for PositionIterator and TermIterator now return *this rather than void. * PositionIterator, PostingIterator, TermIterator and ValueIterator now handle their reference counts in hand-crafted code rather than using intrusive_ptr/RefCntPtr, which means the compiler can inline the destructor and default constructor, so a comparison to an end iterator should now optimise to a simple NULL pointer check, but without the issues which the ValueIteratorEnd_ proxy class approach had (such as not working in templates or some cases of overload resolution). * Enquire: + Previously, Enquire::get_matching_terms_begin() threw InvalidArgumentError if the query was empty. Now we just return an end iterator, which is more consistent with how empty queries behave elsewhere. + Remove the deprecated old-style match spy approach of using a MatchDecider. * Remove deprecated Sorter class and MultiValueSorter subclass. * Xapian::Stem: + Add stemmers for Armenian (hy), Basque (eu), and Catalan (ca). + Stem::operator= now returns a reference to the assigned-to object. testsuite: * OP_SCALE_WEIGHT: Check top weight is non-zero - if it is zero, tests which try to check that OP_SCALE_WEIGHT works will always pass. * testsuite: Check SerialisationError descriptions from Xapian::Weight subclasses mention the weighting scheme name. * Merge queryparsertest and termgentest into apitest. Their testcases now use the backend manager machinery in the testharness, so we don't have to hard-code use of inmemory and chert backends, but instead run them under all backends which support the required features. This fixes some test failures when both chert and glass are disabled due to trying to run spelling tests with the inmemory backend. * Avoid overflowing collection frequency in totaldoclen1. We're trying to test total document length doesn't wrap, so avoid collection freq overflowing in the process, as that triggers errors when running the testsuite under ubsan. We should handle collection frequency overflow better, but that's a separate issue. * Add some test coverage for ESet::get_ebound(). * Fix testcase notermlist1 to check correct table extension - ".glass" not ".DB" (chert doesn't support DB_NO_TERMLIST). * unittest: We can't use Assert() to unit test noexcept code as it throws an exception if it fails. Instead set up macros to set a variable and return if an assertion fails in a unittest testcase, and check that variable in the harness. * Add unit test for internal C_isupper(), etc functions. * If command line option --verbose/-v isn't specified, set the verbosity level from environmental variable VERBOSE. * Re-enable replicate3 for glass, as it no longer fails. * Add more test coverage for get_unique_terms(). * Don't leave an extra fd open when starting xapian-tcpsrv for remotetcp tests. * Extend checkstatsweight1 to check that Weight::get_collection_freq() returns the same number as Database::get_collection_freq(). * queryparsertest: Add testcase for FieldProcessor on boolean prefix with quoted contents. * queryparsertest: Enable some disabled cases which actually work (in some cases with slightly tweaked expected answers which are equivalent to those that were shown). * Make use of the new writable multidatabase feature to simplify the multi-database handling in the test harness. * Change querypairwise1_helper to repeat the query build 100 times, as with a fast modern machine we were sometimes trying with so many subqueries that we would run out of stack. * apitest: Use Xapian::Database::check() in cursordelbug1. (partly addresses TritonDataCenter#238) * apitest: Test Query ops with a single MatchAll subquery. * apitest: New testcase readonlyparentdir1 to ensure that commit works with a read-only parent directory. * tests/generate-api_generated: Test that the string returned by a get_description() method isn't empty. * Use git commit hash in title of test coverage reports generated from a git tree. * Make unittest use the test harness, so it gets all the valgrind and fd leak checks, and other handy features all the other tests have. * Improve test coverage in several places. * Compress generated HTML files in coverage report. matcher: * Fix stats passed to Weight with OP_SYNONYM. Previously the number of unique terms was never calculated, and a term which matched all documents would be optimised to an all-docs postlist, which fails to supply the correct wdf info. * Use floating point calculation for OR synonym freq estimates. The division was being done as an integer division, which means the result was always getting rounded down rather than rounded to the nearest integer. * Fix upper bound on matches for OP_XOR. Due to a reversed conditional, the estimate could be one too low in some cases where the XOR matched all the documents in the database. * Improve lower bound on matches for OP_XOR. Previously the lower bound was always set to 0, which is valid, but we can often do better. * Optimise value range which is a superset of the bounds. If the value frequency is equal to the doccount, such a range is equivalent to MatchAll, and we now avoid having to read the valuestream at all. * Optimise OP_VALUE_RANGE when the upper bound can't be exceeded. In this case, we now use ValueGePostList instead of ValueRangePostList. * Streamline collation of statistics for use by weighting schemes - tests show a 2% or so increase in speed in some cases. * If a term matches all documents and its weight doesn't depend on its wdf, we can optimise it to MatchAll (the previous requirement that maxpart == 0 was unnecessarily strict). * Fix the check for a term which matches all documents to use the sub-db termfreq, not the combined db termfreq. * When we optimise a postlist for a term which matches all documents to use MatchAll, we still need to set a weight object on it to get percentages calculated correctly. * Drop MatchNothing subqueries in OR-like situations in add_subquery() rather than adding them and then handling it later. * Handle the left side of AND_NOT and AND_MAYBE being MatchNothing in add_subquery() rather than in done(). * Handle QueryAndLike with a MatchNothing subquery in add_subquery() rather than done(). * Query: Multi-way operators now store their subquery pointers in a custom class rather than std::vector<Xapian::Query>. The custom class take the same amount of space, or often less. It's particularly efficient when there are two subqueries, which is very desirable as we no longer flatten a subtree of the same operator as we build the query. * Optimise an unweighted query term which matches all the documents in a subdatabase to use the "MatchAll" postlist. (ticket#387) glass backend: * Fix allterms with prefix on glass with uncommitted changes. Glass aims to flush just the relevant postlist changes in this case but the end of the range to flush was wrong, so we'd only actually flush changes for a term exactly matching the prefix. Fixes #721. * Fix Database::check() parsing of glass changes file header. In practice this was unlikely to actually cause problems. * Make glass the default backend. The format should now be stable, except perhaps in the unlikely event that a bug emerges which requires a format change to address. * Don't explicitly store the 2 byte "component_of" counter for the first component of every Btree entry in leaf blocks - instead use one of the upper bits of the length to store a "first component" flag. This directly saves 2 bytes per entry in the Btree, plus additional space due to fewer blocks and fewer levels being needed as a result. This particularly helps the position table, which has a lot of entries, many of them very small. The saving would be expected to be a little less than the saving from the change which shaved 2 bytes of every Btree item in 1.3.4 (since that saved 2 bytes multiple times for large entries which get split into multiple items). A simple test suggests a saving of several percent in total DB size, which fits that. This change reduces the maximum component size to 8194, which affects tables with a 64KB blocksize in normal use and tables with >= 16KB blocksize with full compaction. * Refactor glass backend key comparison - == and < operations are replaced by a compare() function returns negative, 0 or positive (like strcmp(), memcmp() and std::string::compare()). This allows us to avoid a final compare to check for equality when binary chopping, and to terminate early if the binary chop hits the exact entry. * If a cursor is moved to an entry which doesn't exist, we need to step back to the first component of previous entry before we can read its tag. However we often don't actually read its tag (e.g. if we only wanted the key), so make this stepping back lazy so we can avoid doing it when we don't want to read the tag. * Avoid creating std::string objects to hold data when compressing and decompressing tags with zlib. * Store minimum compression length per table in the version file, with 0 meaning "don't compress". Currently you can only change this setting with a hex editor on the file, but now it is there we can later make use of it without needing a database format change. * Database::check() now performs additional consistency checks for glass. Reported by Jean-Francois Dockes and Bob Cargill via xapian-discuss. * Database::check(): check docids don't exceed db_last_docid when checking a single glass table. * We now throw DatabaseCorruptError in a few cases where it's appropriate but we didn't previously, in particular in the case where all the files in a DB have been truncated to zero size (which makes handling of this case consistent with chert). * Fix compaction to a single file which already exists. This was hanging. Noted by Will Greenberg on #xapian. * Shave 2 bytes of every Btree item (which will probably typically reduce database size by several percent). * More compact item format for branch blocks - 2 bytes per item smaller. This means each branch block can branch more ways, reducing the number of Btree levels needed, which is especially helpful for cold-cache search times. * Track an upper bound on spelling word frequency. This isn't currently used, but will be useful for improving the spelling algorithm, and we want to stabilise the glass backend format. See TritonDataCenter#225, reported by Philip Neustrom. * Support 64-bit docids in the glass backend on-disk format. This changes the encoding used by pack_uint_preserving_sort() to one which supports 64 bit values, and is a byte smaller for values 16384-32767, and the same size for all other 32 bit values. Fixes #686, from original report by James Aylett. * Use memcpy() not memmove() when no risk of overlap. * Store length of just the key data itself, allowing keys to be up to 255 bytes long - the previous limit was 252. * Change glass to store DB stats in the version file. Previously we stored them in a special item in the postlist table, but putting them in the version file reduces the number of block reads required to open the database, is simpler to deal with, and means we can potentially recalculate tight upper and lower bounds for an existing database without having to commit a new revision. * Add support for a single-file variant for glass. Currently such databases can only be opened for reading - to create one you need to use xapian-compact (or its API equivalent). You can embed such databases within another file, and open them by passing in a file descriptor open on that file and positioned at the offset the database starts at). Database::check() also supports them. Fixes #666, reported by Will Greenberg (and previously suggested on xapian-discuss by Emmanuel Engelhart). * Avoid potential DB corruption with full-compaction when using 64K blocks. * Where posix_fadvise() is available, use it to prefetch postlist Btree blocks from the level below the root block which will be needed for postlists of terms in the query, and similarly for the docdata table when MSet::fetch() is called. Based on patch by Will Greenberg in #671. * When reporting freelist errors during a database check, distinguish between a block in use and in the freelist, and a block in the freelist more than once. * Fix compaction and database checking for the change to the format of keys in the positionlist table which happened in 1.3.2. * After splitting a block, we always insert the new block in the parent right after the block it was split from - there's no need to binary chop. * Avoid infinite recursion when we hit the end of the freelist block we're reading and the end of the block we're writing at the same time. * Fix freelist handling to allow for the newly loaded first block of the freelist being already used up. * 'brass' backend renamed to 'glass' - we decided to use names in ascending alphabetical order to make it easier to understand which backend is newest, and since 'flint' was used recently, we skipped over 'd', 'e' and 'f'. * Change positionlist keys to be ordered by term first rather than docid first, which helps phrase searching significantly. For more efficient indexing, positionlist changes are now batched up in memory and written out in key order. * Use a separate cursor for each position list - now we're ordering the position B-tree by term first, phrase matching would cause a single cursor to cycle between disparate areas of the B-tree and reread the same blocks repeatedly. * Reference count blocks in the btree cursor, so cursors can cheaply share blocks. This can significantly reduce the amount of memory used by cursors for queries which contain a lot of terms (e.g. wildcards which expand to a lot of terms). * Under glass, optimise the turning of a query into a postlist to reuse the cursor blocks which are the same as the previous term's postlist. This is particularly effective for a wildcard query which expands to a lot of terms. * Keep track of unused blocks in the Btrees using freelists rather than bitmaps. (fixes TritonDataCenter#40) * Eliminate the base files, and instead store the root block and freelist pointers in the "iamglass" file. * When compacting, sync all the tables together at the end. * In DB_DANGEROUS mode, update the version file in-place. * Only actually store the document data if it is non-empty. The table which holds the document data is now lazily created, so won't exist if you never set the document data. * Iterating positional data now decodes it lazily, which should speed up phrases which include common words. * Compress changesets in brass replication. Increments the changeset version. Ticket TritonDataCenter#348 * Restore two missing lines in database checking where we report a block with the wrong level. * When checking if a block was newly allocated in this revision, just look at its revision number rather than consulting the base file's bitmap. remote backend: * Improve handling of invalid remote stub entries: Entries without a colon now give an error rather than being quietly skipped; IPv6 isn't yet supported, but entries with IPv6 addresses now result in saner errors (previously the colons confused the code which looks for a port number). * Fix hook for remote support of user weighting schemes. The commented-out code used entirely the wrong class - now we use the server object we have access to, and forward the method to the class which needs it. * Avoid dividing zero by zero when calculating the average length for an empty database. * Bump remote protocol version to 38.0, due to extra statistics being tracked for weighting. * Make Weight::Internal track if any max_part values are set, so we don't need to serialise them when they've not been set. * Prefix compress list of terms and metadata keys in the remote protocol. This requires a remote protocol major version bump. * When propagating exceptions from a remote backend server, the protocol now sends a numeric code to represent which exception is being propagated, rather than the name of the type, as a number can be turned back into an exception with a simple switch statement and is also less data to transfer. (ticket#471) * Remote protocol (these changes require a protocol major version bump): + Unify REPLY_GREETING and REPLY_UPDATE. + Send (last_docid - doccount) instead of last_docid and (doclen_ubound - doclen_lbound) instead of doclen_ubound. * Remove special check which gives a more helpful error message when a modern client is used against a remote server running Xapian <= 0.9.6. chert backend: * When using 64-bit Xapian::docid, consistently use the actual maximum valid docid value rather instead of the maximum value the type can hold. * Where posix_fadvise() is available, use it to prefetch postlist Btree blocks from the level below the root block which will be needed for postlists of terms in the query, and similarly for the record table when MSet::fetch() is called. Based on patch by Will Greenberg in #671. * Fix problems with get_unique_terms() on a modified chert database. * Fix xapian-check on a single chert table, which seg faulted in 1.3.2. * Improve DBCHECK_FIX: + if fixing a whole database, we now take the revision from the first table we successfully look at, which should be correct in most cases, and is definitely better than trying to determine the revision of each broken table independently. + handle a zero-sized .DB file. + After we successfully regenerate baseA, remove any empty baseB file to prevent it causing problems. Tracked down with help from Phil Hands. * Iterating positional data now decodes it lazily, which should speed up phrases which include common words. flint backend: * Remove flint backend.
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