Clarify item:
Clarify item:

< * Consider use of open/fcntl(O_DIRECT) to minimize OS caching
> * Consider use of open/fcntl(O_DIRECT) to minimize OS caching,
>   especially for WAL writes

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