prometheus

master / unreleased

[FEATURE] Added DBReadOnly to allow opening a database in read only mode.
- DBReadOnly.Blocks() exposes a slice of BlockReaders.
- BlockReader interface - removed MinTime/MaxTime methods and now exposes the full block meta via Meta().
[FEATURE] chunckenc.Chunk.Iterator method now takes a chunckenc.Iterator interface as an argument for reuse.

[FEATURE] Provide option to compress WAL records using Snappy. #609
[BUGFIX] Re-calculate block size when calling block.Delete.
[BUGFIX] Re-encode all head chunks at compaction that are open (being appended to) or outside the Maxt block range. This avoids writing out corrupt data. It happens when snapshotting with the head included.
[BUGFIX] Improved handling of multiple refs for the same series in WAL reading.
[BUGFIX] prometheus_tsdb_compactions_failed_total is now incremented on any compaction failure.
[CHANGE] The meta file BlockStats no longer holds size information. This is now dynamically calculated and kept in memory. It also includes the meta file size which was not included before.
[CHANGE] Create new clean segment when starting the WAL.
[CHANGE] Renamed metric from prometheus_tsdb_wal_reader_corruption_errors to prometheus_tsdb_wal_reader_corruption_errors_total.
[ENHANCEMENT] Improved atomicity of .tmp block replacement during compaction for usual case.
[ENHANCEMENT] Improved postings intersection matching.
[ENHANCEMENT] Reduced disk usage for WAL for small setups.
[ENHANCEMENT] Optimize queries using regexp for set lookups.

[BUGFIX] Calling Close more than once on a querier returns an error instead of a panic.
[BUGFIX] Don't panic and recover nicely when running out of disk space.
[BUGFIX] Correctly handle empty labels.
[BUGFIX] Don't crash on an unknown tombstone ref.
[ENHANCEMENT] Re-add FromData function to create a chunk from bytes. It is used by Cortex and Thanos.
[ENHANCEMENT] Simplify mergedPostings.Seek.
[FEATURE] Added currentSegment metric for the current WAL segment it is being written to.

[CHANGE] tsdb now requires golang 1.12 or higher.
[REMOVED] chunks.NewReader is removed as it wasn't used anywhere.
[REMOVED] FromData is considered unused so was removed.
[FEATURE] Added option WALSegmentSize -1 to disable the WAL.
[BUGFIX] Bugfix in selectOverlappingDirs. Only return the first overlapping blocks.
[BUGFIX] Fsync the meta file to persist it on disk to avoid data loss in case of a host crash.
[BUGFIX] Fix fd and vm_area leak on error path in chunks.NewDirReader.
[BUGFIX] Fix fd and vm_area leak on error path in index.NewFileReader.
[BUGFIX] Force persisting the tombstone file to avoid data loss in case of a host crash.
[BUGFIX] Keep series that are still in WAL in checkpoints.
[ENHANCEMENT] Fast path for EmptyPostings cases in Merge, Intersect and Without.
[ENHANCEMENT] Be smarter in how we look at matchers.
[ENHANCEMENT] PostListings and NotMatcher now public.

[BUGFIX] Update last after appending a non-overlapping chunk in chunks.MergeOverlappingChunks. #539

[FEATURE] Time-ovelapping blocks are now allowed. #370
- Disabled by default and can be enabled via AllowOverlappingBlock option.
- Added MergeChunks function in chunkenc/xor.go to merge 2 time-overlapping chunks.
- Added MergeOverlappingChunks function in chunks/chunks.go to merge multiple time-overlapping Chunk Metas.
- Added MinTime and MaxTime method for BlockReader.
[FEATURE] New dump command to tsdb tool to dump all samples.
[FEATURE] New encoding package for common binary encoding/decoding helpers.
- Added to remove some code duplication.
[ENHANCEMENT] When closing the db any running compaction will be cancelled so it doesn't block.
- NewLeveledCompactor takes a context.
[CHANGE] prometheus_tsdb_storage_blocks_bytes_total is now prometheus_tsdb_storage_blocks_bytes.
[BUGFIX] Improved Postings Merge performance. Fixes a regression from the previous release.
[BUGFIX] LiveReader can get into an infinite loop on corrupt WALs.

[CHANGE] New WALSegmentSize option to override the DefaultOptions.WALSegmentSize. Added to allow using smaller wal files. For example using tmpfs on a RPI to minimise the SD card wear out from the constant WAL writes. As part of this change the DefaultOptions.WALSegmentSize constant was also exposed.
[CHANGE] Empty blocks are not written during compaction #374
[FEATURE] Size base retention through Options.MaxBytes. As part of this change:
- Added new metrics - prometheus_tsdb_storage_blocks_bytes_total, prometheus_tsdb_size_retentions_total, prometheus_tsdb_time_retentions_total
- New public interface SizeReader: Size() int64
- OpenBlock signature changed to take a logger.
[REMOVED] PrefixMatcher is considered unused so was removed.
[CLEANUP] Options.WALFlushInterval is removed as it wasn't used anywhere.
[FEATURE] Add new LiveReader to WAL package. Added to allow live tailing of a WAL segment, used by Prometheus Remote Write after refactor. The main difference between the new reader and the existing Reader is that for LiveReader a call to Next() that returns false does not mean that there will never be more data to read.

[BUGFIX] Fixed most windows test and some actual bugs for unclosed file readers.

[CHANGE] LastCheckpoint() used to return just the segment name and now it returns the full relative path.
[CHANGE] NewSegmentsRangeReader() can now read over miltiple wal ranges by using the new SegmentRange{} struct.
[CHANGE] CorruptionErr{} now also exposes the Segment Dir which is added when displaying any errors.
[CHANGE] Head.Init() is changed to Head.Init(minValidTime int64)
[CHANGE] SymbolTable() renamed to SymbolTableSize() to make the name consistent with the Block{ symbolTableSize uint64 } field.
[CHANGE] wal.Reader{} now exposes Segment() for the current segment being read and Offset() for the current offset.
[FEATURE] tsdbutil analyze subcomand to find churn, high cardinality, etc.