WIP: fix OOM in replay process when dealing with large transactions.

tests/follow-wal2json/Dockerfile

@@ -4,6 +4,7 @@ WORKDIR /usr/src/pgcopydb
 COPY ./copydb.sh copydb.sh
 COPY ./dml.sql dml.sql
 COPY ./ddl.sql ddl.sql
+COPY ./extras.sql extras.sql
 
 USER docker
 CMD /usr/src/pgcopydb/copydb.sh

tests/follow-wal2json/copydb.sh

@@ -18,9 +18,10 @@ psql -o /tmp/d.out -d ${PGCOPYDB_SOURCE_PGURI} -1 -f /usr/src/pagila/pagila-data
 
 # alter the pagila schema to allow capturing DDLs without pkey
 psql -d ${PGCOPYDB_SOURCE_PGURI} -f /usr/src/pgcopydb/ddl.sql
+psql -d ${PGCOPYDB_SOURCE_PGURI} -f /usr/src/pgcopydb/extras.sql
 
 # pgcopydb copy db uses the environment variables
-pgcopydb copy-db --follow --plugin wal2json
+pgcopydb copy-db --follow --plugin wal2json --notice
 
 # cleanup
 pgcopydb stream sentinel get

tests/follow-wal2json/extras.sql

@@ -0,0 +1 @@
+create table foo(f1 int, f2 text);

tests/follow-wal2json/inject.sh

@@ -47,13 +47,20 @@ do
     sleep 1
 done
 
+#
+# produce a single transaction with more contents than fits in a single PIPE
+# buffer/write
+#
+sql="insert into foo select x, repeat('a', x) from generate_series(1, 60000) as t(x)"
+psql -d ${PGCOPYDB_SOURCE_PGURI} -c "${sql}"
+
 # grab the current LSN, it's going to be our streaming end position
 lsn=`psql -At -d ${PGCOPYDB_SOURCE_PGURI} -c 'select pg_current_wal_flush_lsn()'`
 pgcopydb stream sentinel set endpos --current
 pgcopydb stream sentinel get
 
 #
-# Becaure we're using docker-compose --abort-on-container-exit make sure
+# Because we're using docker-compose --abort-on-container-exit make sure
 # that the other process in the pgcopydb service is done before exiting
 # here.
 #