8 Commits (dfcd9cb30237f882b7308bdcbfb0318b22b1e224)

Author	SHA1	Message	Date
Bruce Momjian	807b9e0dff	pgindent run for 9.5	11 years ago
Andres Freund	5aa2350426	Introduce replication progress tracking infrastructure. ... When implementing a replication solution ontop of logical decoding, two related problems exist: * How to safely keep track of replication progress * How to change replication behavior, based on the origin of a row; e.g. to avoid loops in bi-directional replication setups The solution to these problems, as implemented here, consist out of three parts: 1) 'replication origins', which identify nodes in a replication setup. 2) 'replication progress tracking', which remembers, for each replication origin, how far replay has progressed in a efficient and crash safe manner. 3) The ability to filter out changes performed on the behest of a replication origin during logical decoding; this allows complex replication topologies. E.g. by filtering all replayed changes out. Most of this could also be implemented in "userspace", e.g. by inserting additional rows contain origin information, but that ends up being much less efficient and more complicated. We don't want to require various replication solutions to reimplement logic for this independently. The infrastructure is intended to be generic enough to be reusable. This infrastructure also replaces the 'nodeid' infrastructure of commit timestamps. It is intended to provide all the former capabilities, except that there's only 2^16 different origins; but now they integrate with logical decoding. Additionally more functionality is accessible via SQL. Since the commit timestamp infrastructure has also been introduced in 9.5 (commit 73c986add) changing the API is not a problem. For now the number of origins for which the replication progress can be tracked simultaneously is determined by the max_replication_slots GUC. That GUC is not a perfect match to configure this, but there doesn't seem to be sufficient reason to introduce a separate new one. Bumps both catversion and wal page magic. Author: Andres Freund, with contributions from Petr Jelinek and Craig Ringer Reviewed-By: Heikki Linnakangas, Petr Jelinek, Robert Haas, Steve Singer Discussion: 20150216002155.GI15326@awork2.anarazel.de, 20140923182422.GA15776@alap3.anarazel.de, 20131114172632.GE7522@alap2.anarazel.de	11 years ago
Fujii Masao	57aa5b2bb1	Add GUC to enable compression of full page images stored in WAL. ... When newly-added GUC parameter, wal_compression, is on, the PostgreSQL server compresses a full page image written to WAL when full_page_writes is on or during a base backup. A compressed page image will be decompressed during WAL replay. Turning this parameter on can reduce the WAL volume without increasing the risk of unrecoverable data corruption, but at the cost of some extra CPU spent on the compression during WAL logging and on the decompression during WAL replay. This commit changes the WAL format (so bumping WAL version number) so that the one-byte flag indicating whether a full page image is compressed or not is included in its header information. This means that the commit increases the WAL volume one-byte per a full page image even if WAL compression is not used at all. We can save that one-byte by borrowing one-bit from the existing field like hole_offset in the header and using it as the flag, for example. But which would reduce the code readability and the extensibility of the feature. Per discussion, it's not worth paying those prices to save only one-byte, so we decided to add the one-byte flag to the header. This commit doesn't introduce any new compression algorithm like lz4. Currently a full page image is compressed using the existing PGLZ algorithm. Per discussion, we decided to use it at least in the first version of the feature because there were no performance reports showing that its compression ratio is unacceptably lower than that of other algorithm. Of course, in the future, it's worth considering the support of other compression algorithm for the better compression. Rahila Syed and Michael Paquier, reviewed in various versions by myself, Andres Freund, Robert Haas, Abhijit Menon-Sen and many others.	11 years ago
Bruce Momjian	4baaf863ec	Update copyright for 2015 ... Backpatch certain files through 9.0	11 years ago
Heikki Linnakangas	2c03216d83	Revamp the WAL record format. ... Each WAL record now carries information about the modified relation and block(s) in a standardized format. That makes it easier to write tools that need that information, like pg_rewind, prefetching the blocks to speed up recovery, etc. There's a whole new API for building WAL records, replacing the XLogRecData chains used previously. The new API consists of XLogRegister* functions, which are called for each buffer and chunk of data that is added to the record. The new API also gives more control over when a full-page image is written, by passing flags to the XLogRegisterBuffer function. This also simplifies the XLogReadBufferForRedo() calls. The function can dig the relation and block number from the WAL record, so they no longer need to be passed as arguments. For the convenience of redo routines, XLogReader now disects each WAL record after reading it, copying the main data part and the per-block data into MAXALIGNed buffers. The data chunks are not aligned within the WAL record, but the redo routines can assume that the pointers returned by XLogRecGet* functions are. Redo routines are now passed the XLogReaderState, which contains the record in the already-disected format, instead of the plain XLogRecord. The new record format also makes the fixed size XLogRecord header smaller, by removing the xl_len field. The length of the "main data" portion is now stored at the end of the WAL record, and there's a separate header after XLogRecord for it. The alignment padding at the end of XLogRecord is also removed. This compansates for the fact that the new format would otherwise be more bulky than the old format. Reviewed by Andres Freund, Amit Kapila, Michael Paquier, Alvaro Herrera, Fujii Masao.	11 years ago
Bruce Momjian	7e04792a1c	Update copyright for 2014 ... Update all files in head, and files COPYRIGHT and legal.sgml in all back branches.	12 years ago
Heikki Linnakangas	2ff6555313	Use the right timeline when beginning to stream from master. ... The xlogreader refactoring broke the logic to decide which timeline to start streaming from. XLogPageRead() uses the timeline history to check which timeline the requested WAL position falls into. However, after the refactoring, XLogPageRead() is always first called with the first page in the segment, to verify the segment header, and only then with the actual WAL position we're interested in. That first read of the segment's header made XLogPageRead() to always start streaming from the old timeline containing the segment header, not the timeline containing the actual record, if there was a timeline switch within the segment. I thought I fixed this yesterday, but that fix was too narrow and only fixed this for the corner-case that the timeline switch happened in the first page of the segment. To fix this more robustly, pass explicitly the position of the record we're actually interested in to XLogPageRead, and use that to decide which timeline to read from, rather than deduce it from the page and offset. Per report from Fujii Masao.	13 years ago
Alvaro Herrera	7fcbf6a405	Split out XLog reading as an independent facility ... This new facility can not only be used by xlog.c to carry out crash recovery, but also by external programs. By supplying a function to read XLog pages from somewhere, all the WAL reading can be used for completely different purposes. For the standard backend use, the behavior should be pretty much the same as previously. As for non-backend programs, an hypothetical pg_xlogdump program is now closer to reality, but some more backend support is still necessary. This patch was originally submitted by Andres Freund in a different form, but Heikki Linnakangas opted for and authored another design of the concept. Andres has advanced the patch since Heikki's initial version. Review and some (mostly cosmetics) changes by me.	13 years ago