PostgreSQL 3-6 Smgr

接口

void smgrcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo); // 创建文件
void smgrdounlink(SMgrRelation reln, bool isRedo);

SMgrRelation smgropen(RelFileNode rnode, BackendId backend);
void smgrclose(SMgrRelation reln);

void smgrwrite(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, char *buffer, bool skipFsync);
void smgrread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, char *buffer);
void smgrextend(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, char *buffer, bool skipFsync);

调用关系

// 索引模块
btbuildempty()
    smgrwrite(metapage)
_bt_blwritepage()
    smgrwrite()
spgbuildempty()
    smgrwrite()

|- FlushBuffer() ...
|- FlushRelationBuffers()
|- LocalBufferAlloc()
    smgrwrite()

// FlushBuffer
|- BufferAlloc() // readBuffer时，申请一个buffer，可能调用页面淘汰算法
|- FlushDatabaseBuffers()
|- FlushRelationBuffers()
|- FlushOneBuffer()
    FlushBuffer()

// FlushOneBuffer
XLogReadBufferForRedoExtended()
    FlushOneBuffer()

// FlushRelationBuffers
|- heap_sync()
|- ATExecSetTableSpace() // ALTER TABLE SET TABLESPACE
    FlushRelationBuffers()
// heap_sync when HEAP_INSERT_SKIP_WAL
|- intorel_shutdown()
|- CopyFrom()
|- transientrel_shutdown()
|- ATRewriteTable()
    heap_sync()

// FlushDatabaseBuffers
dbase_redo()
    FlushDatabaseBuffers()

write时机：

readBuffer时，如果buffer不在内存，且共享缓冲池已满，调用页面置换算法进行刷盘
alter table set table space
copy