LSN now visible in json

.gitignore

@@ -0,0 +1,2 @@
+*.o
+*.so

Makefile

@@ -1,55 +1,8 @@
-# contrib/wal2json/Makefile
+MODULES = wal2json
 
-MODULE_big = wal2json
-OBJS = wal2json.o
+REGRESS = basic
+REGRESS_OPTS = --temp-config=./logical.conf
 
-# Note: because we don't tell the Makefile there are any regression tests,
-# we have to clean those result files explicitly
-EXTRA_CLEAN = -r $(pg_regress_clean_files)
-
-ifdef USE_PGXS
 PG_CONFIG = pg_config
 PGXS := $(shell $(PG_CONFIG) --pgxs)
 include $(PGXS)
-else
-subdir = contrib/wal2json
-top_builddir = ../..
-include $(top_builddir)/src/Makefile.global
-include $(top_srcdir)/contrib/contrib-global.mk
-endif
-
-# Disabled because these tests require "wal_level=logical", which
-# typical installcheck users do not have (e.g. buildfarm clients).
-installcheck:;
-
-# But it can nonetheless be very helpful to run tests on preexisting
-# installation, allow to do so, but only if requested explicitly.
-installcheck-force: regresscheck-install-force
-
-check: regresscheck
-
-submake-regress:
-	$(MAKE) -C $(top_builddir)/src/test/regress all
-
-submake-test_decoding:
-	$(MAKE) -C $(top_builddir)/contrib/test_decoding
-
-REGRESSCHECKS=insert1 update1 update2 update3 update4 delete1 delete2 delete3 delete4 \
-			  savepoint specialvalue toast bytea
-
-regresscheck: all | submake-regress submake-test_decoding
-	$(pg_regress_check) \
-		--temp-config $(top_srcdir)/contrib/test_decoding/logical.conf \
-		--temp-install=./tmp_check \
-		--extra-install=contrib/wal2json \
-		--extra-install=contrib/test_decoding \
-		$(REGRESSCHECKS)
-
-regresscheck-install-force: | submake-regress submake-test_decoding
-	$(pg_regress_installcheck) \
-		--extra-install=contrib/wal2json \
-		--extra-install=contrib/test_decoding \
-		$(REGRESSCHECKS)
-
-PHONY: check submake-regress submake-test_decoding \
-	regresscheck regresscheck-install-force

README.md

@@ -1,4 +1,36 @@
-wal2json
-========
+# wal2json
 
 JSON output plugin for changeset extraction
+
+### Forked
+
+This is a fork of the great utility at https://github.com/eulerto/wal2json
+
+I take no credit for the C code. Just a little packaging. 
+
+Unfortunately, the source repository didn't make it into the postgres mainline source. Which makes it a bit tricky to compile with this makefile.  I updated the makefile, so it works.
+
+
+### Install Steps
+
+(On Debian)
+
+```
+# You need postgres 9.4 installed on your machine, you probably have it already
+sudo apt-get install postgres-9.4
+sudo apt-get install postgres-contrib-9.4
+
+# to compile this code, you need the following
+sudo apt-get install build-essential
+sudo apt-get build-dep postgresql-9.4
+sudo apt-get install postgres-server-dev-9.4
+
+# now go into the directory and...
+make
+sudo make install
+```
+
+
+### Logical Replication
+
+You need to know quite a few things about logical replication to make use of this.  If this is new to you, please check out [the official postgres documentation](http://www.postgresql.org/docs/9.4/static/logicaldecoding-example.html).  You can replace 'test_decoding' with 'wal2json' to see the magic of this plugin.

logical.conf

@@ -0,0 +1,2 @@
+wal_level = logical
+max_replication_slots = 1

wal2json.c

@@ -26,6 +26,7 @@
 #include "utils/builtins.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
+#include "utils/pg_lsn.h"
 #include "utils/rel.h"
 #include "utils/relcache.h"
 #include "utils/syscache.h"
@@ -40,6 +41,7 @@ typedef struct
 {
 	MemoryContext context;
 	bool		include_xids;		/* include transaction ids */
+	bool		include_lsn;		/* include lsn for safer syncing */
 	bool		include_timestamp;	/* include transaction timestamp */
 	bool		include_schemas;	/* qualify tables */
 	bool		include_types;		/* include data types */
@@ -91,6 +93,7 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt, bool is
 										ALLOCSET_DEFAULT_INITSIZE,
 										ALLOCSET_DEFAULT_MAXSIZE);
 	data->include_xids = true;
+	data->include_lsn = true;
 	data->include_timestamp = false;
 	data->include_schemas = true;
 	data->include_types = true;
@@ -160,6 +163,20 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt, bool is
 						 errmsg("could not parse value \"%s\" for parameter \"%s\"",
 							 strVal(elem->arg), elem->defname)));
 		}
+		else if (strcmp(elem->defname, "include-lsn") == 0)
+		{
+			/* If option does not provide a value, it means its value is true */
+			if (elem->arg == NULL)
+			{
+				elog(LOG, "include-lsn argument is null");
+				data->include_xids = true;
+			}
+			else if (!parse_bool(strVal(elem->arg), &data->include_lsn))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						 errmsg("could not parse value \"%s\" for parameter \"%s\"",
+							 strVal(elem->arg), elem->defname)));
+		}
 		else
 		{
 			elog(WARNING, "option %s = %s is unknown",
@@ -194,6 +211,12 @@ pg_decode_begin_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 	if (data->include_xids)
 		appendStringInfo(ctx->out, "\t\"xid\": %u,\n", txn->xid);
 
+	if (data->include_lsn) {
+		char *lsn_str = DatumGetCString(DirectFunctionCall1(pg_lsn_out, ctx->write_location));
+		appendStringInfo(ctx->out, "\t\"start_lsn\": \"%s\",\n", lsn_str);
+		pfree(lsn_str);
+	}
+
 	if (data->include_timestamp)
 		appendStringInfo(ctx->out, "\t\"timestamp\": \"%s\",\n", timestamptz_to_str(txn->commit_time));
 
@@ -219,7 +242,14 @@ pg_decode_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	/* Transaction ends */
 	OutputPluginPrepareWrite(ctx, true);
 
-	appendStringInfoString(ctx->out, "\t]\n}");
+	/* Make sure the commas and new lines work with and without include_lsn */
+	appendStringInfoString(ctx->out, "\t]");
+	if (data->include_lsn) {
+		char *lsn_str = DatumGetCString(DirectFunctionCall1(pg_lsn_out, commit_lsn));
+		appendStringInfo(ctx->out, ",\n\t\"end_lsn\": \"%s\"", lsn_str);
+		pfree(lsn_str);
+	}
+	appendStringInfoString(ctx->out, "\n}");
 
 	OutputPluginWrite(ctx, true);
 }