Update hypopg_index.cpp

src/gausskernel/dbmind/kernel/hypopg_index.cpp

@@ -127,6 +127,12 @@ void InitHypopg()
     }
     isExplain = false;
 }
+/*
+SQLAllocConnect() allocates a connection handle and associated resources within the 
+environment that is identified by the input environment handle. Call SQLGetInfo() with 
+fInfoType set to SQL_ACTIVE_CONNECTIONS to query the number of connections that
+can be allocated at any one time. SQLAllocEnv() must be called before calling this function.*/
+
 
 /*
 Set_hypopg_prehook function:
@@ -185,7 +191,18 @@ static Oid hypo_getNewOid(Oid relid)
 
     /* Open the relation on which we want a new OID */
     relation = heap_open(relid, AccessShareLock);
-
+  
+/*In PostgreSQL, AccessShareLock is a lock type used to 
+control concurrent access to database objects. It is a read 
+lock that allows multiple transactions to read from the same 
+object at the same time, but it prevents concurrent transactions 
+from acquiring conflicting locks, such as write locks or exclusive locks.
+When a transaction obtains AccessShareLock on an object, other
+transactions can also obtain AccessShareLock on the same object. 
+This means that multiple transactions can read objects at the same
+time without interfering with each other.*/
+  
+  
     reltablespace = relation->rd_rel->reltablespace;
     relpersistence = relation->rd_rel->relpersistence;
 
@@ -300,6 +317,7 @@ List *get_table_indexes(Oid oid)
     heap_close(rel, NoLock);
     return indexes;
 }
+/*Read-only here will not cause deadlock, so use NoLock lock.*/
 
 /* Return the names of all the columns involved in the index. */