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Add DTM implementation based on timestamps
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‎contrib/pg_tsdtm/Makefile

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MODULE_big = pg_dtm
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OBJS = pg_dtm.o
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EXTENSION = pg_dtm
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DATA = pg_dtm--1.0.sql
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ifdef USE_PGXS
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PG_CONFIG = pg_config
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PGXS := $(shell $(PG_CONFIG) --pgxs)
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include $(PGXS)
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else
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subdir = contrib/pg_dtm
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top_builddir = ../..
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include $(top_builddir)/src/Makefile.global
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include $(top_srcdir)/contrib/contrib-global.mk
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endif

‎contrib/pg_tsdtm/README

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===
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dtm
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===
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Distributed transaction management tools for PostgreSQL.
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--------------------
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Communication scheme
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--------------------
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.- Backend -.
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/ \
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/ \
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DTM ---- Backend ---- Coordinator
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\ /
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\ /
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`- Backend -´
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-----------------------
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Coordinator-Backend API
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-----------------------
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This API includes a set of postgres procedures that
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the coordinator can call with "select" statement.
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extend_transaction (n integer) -> (higcid gcid)
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join_transaction (higcid gcid) -> ()
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FIXME: add procedures that would start and finish 2pc
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----------
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libdtm api
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----------
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typedef unsigned long long cid_t;
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// Connects to the specified DTM.
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DTMConn DtmConnect(char *host, int port);
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// Disconnects from the DTM. Do not use the 'dtm' pointer after this call, or
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// bad things will happen.
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void DtmDisconnect(DTMConn dtm);
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// Asks DTM for the first 'gcid' with unknown status. This 'gcid' is used as a
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// kind of snapshot. Returns the 'gcid' on success, or INVALID_GCID otherwise.
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cid_t DtmGlobalGetNextCid(DTMConn dtm);
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// Prepares a commit. Returns the 'gcid' on success, or INVALID_GCID otherwise.
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cid_t DtmGlobalPrepare(DTMConn dtm);
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// Finishes a given commit with 'committed' status. Returns 'true' on success,
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// 'false' otherwise.
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bool DtmGlobalCommit(DTMConn dtm, cid_t gcid);
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// Finishes a given commit with 'aborted' status.
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void DtmGlobalRollback(DTMConn dtm, cid_t gcid);
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// Gets the status of the commit identified by 'gcid'. Returns the status on
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// success, or -1 otherwise.
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int DtmGlobalGetTransStatus(DTMConn dtm, cid_t gcid);
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--------------------
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Backend-DTM Protocol
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--------------------
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DTM <--> Backend:
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<- 'p'<hex16 self> - "prepare"
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-> '+'<hex16 gcid> - "commit prepared"
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-> '-' - "something went wrong"
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<- 'c'<hex16 gcid> - "commit"
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-> '+' - "commit saved"
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-> '-' - "something went wrong"
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<- 'a'<hex16 gcid> - "abort"
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-> '+' - "abort saved"
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-> '-' - "something went wrong"
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<- 'h' - "horizon"
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-> '+'<hex16 gcid> - "here is a gcid you can use as a snapshot"
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-> '-' - "something went wrong"
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<- 's'<hex16 gcid> - "status"
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-> '+''c|a|?' - "here is the transaction status"
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(c)ommitted, (a)borted or (?)unknown
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-> '-' - "something went wrong"
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Backend disconnection is considered as an abort of all incomplete commits
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prepared by that backend.

‎contrib/pg_tsdtm/expected/test_dtm.out

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‎contrib/pg_tsdtm/pg_dtm--1.0.sql

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-- complain if script is sourced in psql, rather than via CREATE EXTENSION
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\echo Use "CREATE EXTENSION pg_dtm" to load this file. \quit
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CREATE FUNCTION dtm_register_node(id integer) RETURNS void
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AS 'MODULE_PATHNAME','dtm_register_node'
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LANGUAGE C;
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CREATE FUNCTION dtm_extend(gtid cstring default null) RETURNS bigint
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AS 'MODULE_PATHNAME','dtm_extend'
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LANGUAGE C;
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CREATE FUNCTION dtm_access(snapshot bigint, gtid cstring default null) RETURNS bigint
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AS 'MODULE_PATHNAME','dtm_access'
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LANGUAGE C;
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CREATE FUNCTION dtm_begin_prepare(gtid cstring, coordinator integer) RETURNS void
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AS 'MODULE_PATHNAME','dtm_begin_prepare'
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LANGUAGE C;
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CREATE FUNCTION dtm_prepare(gtid cstring, csn bigint) RETURNS bigint
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AS 'MODULE_PATHNAME','dtm_prepare'
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LANGUAGE C;
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CREATE FUNCTION dtm_end_prepare(gtid cstring, csn bigint) RETURNS void
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AS 'MODULE_PATHNAME','dtm_end_prepare'
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LANGUAGE C;

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