资源管理器（Resource Manager，rmgr）
PostgreSQL将WAL日志划分为不同的资源管理器（Resource Managers，RM），核心是为了实现关注点分离：
- 每个存储模块都有自己的REDO逻辑。
- 逻辑解码器可以只监听它关心的RM类型。
- 可扩展性：自定义的表访问方法（Table Access Method）或自定义索引需要有自己的WAL。
OpenGauss
:/root/openGauss-server/src/include/access/xlog_internal.h:210-231
```cpp
/*
* Method table for resource managers.
*
* This struct must be kept in sync with the PG_RMGR definition in
* rmgr.cpp.
*
* RmgrTable[] is indexed by RmgrId values (see rmgrlist.h).
*/
typedef struct RmgrData {
const char* rm_name;
void (*rm_redo)(XLogReaderState* record);
void (*rm_desc)(StringInfo buf, XLogReaderState* record);
void (*rm_startup)(void);
void (*rm_cleanup)(void);
bool (*rm_safe_restartpoint)(void);
int (*rm_undo)(URecVector *urecvector, int startIdx, int endIdx,
TransactionId xid, Oid reloid, Oid partitionoid,
BlockNumber blkno, bool isFullChain,
int preRetCode, Oid *preReloid, Oid *prePartitionoid, bool is_sync_rollback);
void (*rm_undo_desc) (StringInfo buf, UndoRecord *record);
const char* (*rm_type_name)(uint8 subtype);
} RmgrData;PostgreSQL 19
/*
* Method table for resource managers.
*
* This struct must be kept in sync with the PG_RMGR definition in
* rmgr.c.
*
* rm_identify must return a name for the record based on xl_info (without
* reference to the rmid). For example, XLOG_BTREE_VACUUM would be named
* "VACUUM". rm_desc can then be called to obtain additional detail for the
* record, if available (e.g. the last block).
*
* rm_mask takes as input a page modified by the resource manager and masks
* out bits that shouldn't be flagged by wal_consistency_checking.
*
* RmgrTable[] is indexed by RmgrId values (see rmgrlist.h). If rm_name is
* NULL, the corresponding RmgrTable entry is considered invalid.
*/
typedef struct RmgrData
{
const char *rm_name;
void (*rm_redo) (XLogReaderState *record);
void (*rm_desc) (StringInfo buf, XLogReaderState *record);
const char *(*rm_identify) (uint8 info);
void (*rm_startup) (void);
void (*rm_cleanup) (void);
void (*rm_mask) (char *pagedata, BlockNumber blkno);
void (*rm_decode) (struct LogicalDecodingContext *ctx,
struct XLogRecordBuffer *buf);
} RmgrData;逻辑解码实现差异
PostgreSQL 14
rm_decode 是在 PostgreSQL 14 中引入的。1
Make logical decoding a part of the rmgr.
Add a new rmgr method, rm_decode, and use that rather than a switch statement.
In preparation for rmgr extensibility.
OpenGauss
散落在logical/decode.cpp中，架构耦合，新增模块时容易忘记适配。
bool IsRecordProcess(XLogReaderState *record)
{
switch ((RmgrIds)XLogRecGetRmid(record)) {
case RM_SMGR_ID:
case RM_CLOG_ID:
case RM_DBASE_ID:
case RM_TBLSPC_ID:
case RM_MULTIXACT_ID:
case RM_RELMAP_ID:
case RM_BTREE_ID:
case RM_HASH_ID:
case RM_GIN_ID:
case RM_GIST_ID:
case RM_SEQ_ID:
case RM_SPGIST_ID:
case RM_SLOT_ID:
case RM_BARRIER_ID:
case RM_UHEAP2_ID:
case RM_UNDOLOG_ID:
case RM_UHEAPUNDO_ID:
case RM_UNDOACTION_ID:
case RM_UBTREE_ID:
case RM_UBTREE2_ID:
case RM_UBTREE3_ID:
case RM_UBTREE4_ID:
case RM_SEGPAGE_ID:
case RM_REPLORIGIN_ID:
#ifdef ENABLE_MOT
case RM_MOT_ID:
#endif
return false;
default:
return true;
}
}