Add some test scaffolding to allow cache-flush stress testing (and I do mean stress ... system is orders of magnitude slower with this enabled).
Add some test scaffolding to allow cache-flush stress testing (and I do
mean stress ... system is orders of magnitude slower with this enabled).

Quikling/gpdb,Postgres-XL/Postgres-XL,foyzur/gpdb,tangp3/gpdb,zeroae/postgres-xl,CraigHarris/gpdb,Postgres-XL/Postgres-XL,adam8157/gpdb,randomtask1155/gpdb,lintzc/gpdb,postmind-net/postgres-xl,tpostgres-projects/tPostgres,Quikling/gpdb,adam8157/gpdb,xuegang/gpdb,lintzc/gpdb,xinzweb/gpdb,edespino/gpdb,ahachete/gpdb,rvs/gpdb,kmjungersen/PostgresXL,oberstet/postgres-xl,atris/gpdb,lintzc/gpdb,pavanvd/postgres-xl,zaksoup/gpdb,ovr/postgres-xl,royc1/gpdb,cjcjameson/gpdb,rvs/gpdb,yuanzhao/gpdb,yuanzhao/gpdb,foyzur/gpdb,0x0FFF/gpdb,Chibin/gpdb,randomtask1155/gpdb,snaga/postgres-xl,rvs/gpdb,ovr/postgres-xl,arcivanov/postgres-xl,techdragon/Postgres-XL,xuegang/gpdb,foyzur/gpdb,rubikloud/gpdb,arcivanov/postgres-xl,Chibin/gpdb,arcivanov/postgres-xl,lpetrov-pivotal/gpdb,adam8157/gpdb,janebeckman/gpdb,royc1/gpdb,Chibin/gpdb,lisakowen/gpdb,rubikloud/gpdb,kmjungersen/PostgresXL,tangp3/gpdb,edespino/gpdb,zaksoup/gpdb,randomtask1155/gpdb,kmjungersen/PostgresXL,yazun/postgres-xl,atris/gpdb,CraigHarris/gpdb,cjcjameson/gpdb,cjcjameson/gpdb,rvs/gpdb,yuanzhao/gpdb,CraigHarris/gpdb,xinzweb/gpdb,0x0FFF/gpdb,yuanzhao/gpdb,Chibin/gpdb,0x0FFF/gpdb,greenplum-db/gpdb,tpostgres-projects/tPostgres,zaksoup/gpdb,lisakowen/gpdb,tpostgres-projects/tPostgres,greenplum-db/gpdb,techdragon/Postgres-XL,lisakowen/gpdb,tangp3/gpdb,CraigHarris/gpdb,jmcatamney/gpdb,chrishajas/gpdb,lpetrov-pivotal/gpdb,jmcatamney/gpdb,ahachete/gpdb,lpetrov-pivotal/gpdb,randomtask1155/gpdb,snaga/postgres-xl,janebeckman/gpdb,xuegang/gpdb,oberstet/postgres-xl,rubikloud/gpdb,royc1/gpdb,0x0FFF/gpdb,xinzweb/gpdb,xinzweb/gpdb,kaknikhil/gpdb,techdragon/Postgres-XL,foyzur/gpdb,kaknikhil/gpdb,0x0FFF/gpdb,tangp3/gpdb,janebeckman/gpdb,yazun/postgres-xl,tangp3/gpdb,kmjungersen/PostgresXL,janebeckman/gpdb,ovr/postgres-xl,lpetrov-pivotal/gpdb,snaga/postgres-xl,royc1/gpdb,greenplum-db/gpdb,50wu/gpdb,atris/gpdb,ahachete/gpdb,arcivanov/postgres-xl,xuegang/gpdb,ahachete/gpdb,chrishajas/gpdb,atris/gpdb,Quikling/gpdb,chrishajas/gpdb,xuegang/gpdb,adam8157/gpdb,randomtask1155/gpdb,ahachete/gpdb,yuanzhao/gpdb,atris/gpdb,oberstet/postgres-xl,jmcatamney/gpdb,lintzc/gpdb,pavanvd/postgres-xl,ashwinstar/gpdb,kaknikhil/gpdb,greenplum-db/gpdb,zeroae/postgres-xl,Chibin/gpdb,adam8157/gpdb,ashwinstar/gpdb,edespino/gpdb,zeroae/postgres-xl,chrishajas/gpdb,yuanzhao/gpdb,arcivanov/postgres-xl,foyzur/gpdb,ahachete/gpdb,yazun/postgres-xl,janebeckman/gpdb,zeroae/postgres-xl,rvs/gpdb,ashwinstar/gpdb,janebeckman/gpdb,lpetrov-pivotal/gpdb,kaknikhil/gpdb,cjcjameson/gpdb,greenplum-db/gpdb,arcivanov/postgres-xl,CraigHarris/gpdb,postmind-net/postgres-xl,0x0FFF/gpdb,Quikling/gpdb,zaksoup/gpdb,xinzweb/gpdb,randomtask1155/gpdb,50wu/gpdb,jmcatamney/gpdb,chrishajas/gpdb,adam8157/gpdb,50wu/gpdb,techdragon/Postgres-XL,CraigHarris/gpdb,greenplum-db/gpdb,royc1/gpdb,50wu/gpdb,lisakowen/gpdb,snaga/postgres-xl,yuanzhao/gpdb,Chibin/gpdb,Postgres-XL/Postgres-XL,janebeckman/gpdb,chrishajas/gpdb,xuegang/gpdb,foyzur/gpdb,rubikloud/gpdb,rubikloud/gpdb,greenplum-db/gpdb,Chibin/gpdb,cjcjameson/gpdb,rubikloud/gpdb,kaknikhil/gpdb,ahachete/gpdb,Quikling/gpdb,oberstet/postgres-xl,lintzc/gpdb,rubikloud/gpdb,Postgres-XL/Postgres-XL,jmcatamney/gpdb,cjcjameson/gpdb,Quikling/gpdb,50wu/gpdb,xinzweb/gpdb,postmind-net/postgres-xl,lintzc/gpdb,lintzc/gpdb,randomtask1155/gpdb,adam8157/gpdb,tpostgres-projects/tPostgres,Quikling/gpdb,jmcatamney/gpdb,foyzur/gpdb,xuegang/gpdb,cjcjameson/gpdb,kaknikhil/gpdb,lisakowen/gpdb,50wu/gpdb,CraigHarris/gpdb,xuegang/gpdb,tpostgres-projects/tPostgres,lisakowen/gpdb,lintzc/gpdb,lintzc/gpdb,rvs/gpdb,Chibin/gpdb,kaknikhil/gpdb,greenplum-db/gpdb,ahachete/gpdb,Quikling/gpdb,tangp3/gpdb,ashwinstar/gpdb,kaknikhil/gpdb,zeroae/postgres-xl,rubikloud/gpdb,Quikling/gpdb,rvs/gpdb,jmcatamney/gpdb,rvs/gpdb,oberstet/postgres-xl,Chibin/gpdb,janebeckman/gpdb,zaksoup/gpdb,cjcjameson/gpdb,zaksoup/gpdb,yuanzhao/gpdb,edespino/gpdb,janebeckman/gpdb,ashwinstar/gpdb,atris/gpdb,yuanzhao/gpdb,xinzweb/gpdb,yazun/postgres-xl,ovr/postgres-xl,lisakowen/gpdb,Quikling/gpdb,atris/gpdb,edespino/gpdb,50wu/gpdb,kmjungersen/PostgresXL,chrishajas/gpdb,Chibin/gpdb,atris/gpdb,Postgres-XL/Postgres-XL,edespino/gpdb,royc1/gpdb,royc1/gpdb,ashwinstar/gpdb,postmind-net/postgres-xl,foyzur/gpdb,rvs/gpdb,pavanvd/postgres-xl,xuegang/gpdb,janebeckman/gpdb,kaknikhil/gpdb,chrishajas/gpdb,lpetrov-pivotal/gpdb,lpetrov-pivotal/gpdb,tangp3/gpdb,pavanvd/postgres-xl,royc1/gpdb,edespino/gpdb,ovr/postgres-xl,snaga/postgres-xl,rvs/gpdb,0x0FFF/gpdb,edespino/gpdb,cjcjameson/gpdb,postmind-net/postgres-xl,adam8157/gpdb,lpetrov-pivotal/gpdb,edespino/gpdb,cjcjameson/gpdb,jmcatamney/gpdb,yazun/postgres-xl,yuanzhao/gpdb,tangp3/gpdb,randomtask1155/gpdb,CraigHarris/gpdb,zaksoup/gpdb,ashwinstar/gpdb,techdragon/Postgres-XL,CraigHarris/gpdb,kaknikhil/gpdb,ashwinstar/gpdb,xinzweb/gpdb,50wu/gpdb,pavanvd/postgres-xl,lisakowen/gpdb,0x0FFF/gpdb,edespino/gpdb,zaksoup/gpdb