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C OCI Function Server Round-Trips

This appendix provides information about server round-trips incurred during various OCI calls. A server round-trip is defined as the trip from the client to the server and back to the client. This information can help programmers to determine the most efficient way to accomplish a particular task in an application.

This appendix contains these topics:

Overview of Server Round-Trips

This appendix provides information about server round-trips incurred during various OCI calls. This information can be useful when determining the most efficient way to accomplish a particular task in an application.

Relational Function Round-Trips

Table C-1 lists the number of server round-trips required by each OCI relational function.

Table C-1 Server Round-Trips for Relational Operations

Function Number of Server Round-Trips

OCIBreak()

1

OCIDBShutdown()

1

OCIDBStartup()

1

OCIEnvCreate()

0

OCIEnvInit()

0

OCIErrorGet()

0

OCIInitialize()

0

OCILdaToSvcCtx()

0

OCILogoff()

1

OCILogon()

1

OCILogon2()

Connection pool or session pool: same as OCISessionGet()

Normal: 2 (depends on authentication and TAF situation)

OCIPasswordChange()

1

OCIPing()

1

OCIReset()

0

OCIServerAttach()

1

OCIServerDetach()

1

OCIServerVersion()

1

OCISessionBegin()

1

OCISessionEnd()

1

OCISessionGet()

Session pool: 0 - increment of logins. Connection pool: 1 to (1+ (increment * logins)). Depends on cache hit: one for the user session, optional increment for primary sessions.

Normal: 1 login

OCISessionPoolCreate()

sessMin * logins

OCISessionPoolDestroy()

Sessions in cache * logoffs

OCISessionRelease()

Session pooling: 0, except when explicit session destroys flag set

Normal: 1 login

OCIStmtExecute()

1

OCIStmtFetch()

0 or 1

OCIStmtFetch2()

0 in prefetch, otherwise 1

OCIStmtGetPieceInfo()

1

OCIStmtPrepare()

0

OCIStmtSetPieceInfo()

0

OCISvcCtxToLda()

0

OCITerminate()

1

OCITransCommit()

1

OCITransDetach()

1

OCITransForget()

1

OCITransPrepare()

1

OCItransRollback()

1

OCITransStart()

1

OCIUserCallbackGet()

0

OCIUserCallbackRegister()

0


LOB Function Round-Trips

Table C-2 lists the server round-trips incurred by the OCILob calls.

Note:

To minimize the number of round-trips, you can use the data interface for LOBs. You can bind or define character data for a CLOB column or RAW data for a BLOB column.

See Also:

For calls whose number of round-trips is "0 or 1," if LOB buffering is on, and the request can be satisfied in the client, no round-trips are incurred.

Table C-2 Server Round-Trips for OCILob Calls

Function Number of Server Round-Trips

OCILobAppend()

1

OCILobArrayRead()

1

OCILobArraywrite()

1

OCILobAssign()

0

OCILobCharSetForm()

0

OCILobCharSetId()

0

OCILobClose()

1

OCILobCopy()

1

OCILobCopy2()

1

OCILobCreateTemporary()

1

OCILobDisableBuffering()

0

OCILobEnableBuffering()

0

OCILobErase()

1

OCILobErase2()

1

OCILobFileClose()

1

OCILobFileCloseAll()

1

OCILobFileExists()

1

OCILobFileGetName()

0

OCILobFileIsOpen()

1

OCILobFileOpen()

1

OCILobFileSetName()

0

OCILobFlushBuffer()

1 for each modified page in the buffer for this LOB

OCILobFreeTemporary()

1

OCILobGetChunkSize()

1

OCILobGetLength()

1

OCILobGetLength2()

1

OCILobGetStorageLimit()

1

OCILobIsEqual()

0

OCILobIsOpen()

1

OCILobIsTemporary()

0

OCILobLoadFromFile()

1

OCILobLoadFromFile2()

1

OCILobLocatorAssign()

1 round-trip if either the source or the destination locator refers to a temporary LOB

OCILobLocatorIsInit()

0

OCILobOpen()

1

OCILobRead()

0 or 1

OCILobRead2()

0 or 1

OCILobTrim()

1

OCILobTrim2()

1

OCILobWrite()

0 or 1

OCILobWrite2()

0 or 1

OCILobWriteAppend()

0 or 1

OCILobWriteAppend2()

0 or 1


Object and Cache Function Round-Trips

Table C-3 lists the number of server round-trips required for the object and cache functions. These values assume the cache is in a warm state, meaning that the type descriptor objects required by the application have been loaded.

Table C-3 Server Round-Trips for Object and Cache Functions

Function Number of Server Round-Trips

OCICacheFlush()

1

OCICacheFree()

0

OCICacheRefresh()

1

OCICacheUnmark()

0

OCICacheUnpin()

0

OCIObjectArrayPin()

1

OCIObjectCopy()

0

OCIObjectExists()

0

OCIObjectFlush()

1

OCIObjectFree()

0

OCIObjectGetInd()

0

OCIObjectGetObjectRef()

0

OCIObjectGetTypeRef()

0

OCIObjectIsDirty()

0

OCIObjectIsLocked()

0

OCIObjectLock()

1

OCIObjectMarkDelete()

0

OCIObjectMarkDeleteByRef()

0

OCIObjectMarkUpdate()

0

OCIObjectNew()

0

OCIObjectPin()

1; 0 if the desired object is already in cache

OCIObjectPinCountReset()

0

OCIObjectPinTable()

1

OCIObjectRefresh()

1

OCIObjectUnmark()

0

OCIObjectUnmarkByRef()

0

OCIObjectUnpin()

0


Describe Operation Round-Trips

Table C-4 lists the number of server round-trips required by OCIDescribeAny(), OCIAttrGet(), and OCIParamGet().

Table C-4 Server Round-Trips for Describe Operations

Function Number of Server Round-Trips

OCIAttrGet()

2 round-trips to describe a type if the type objects are not in the object cache

1 round-trip for each collection element, or each type attribute, method, or method argument descriptor. 1 more round-trip if using OCI_ATTR_TYPE_NAME, or OCI_ATTR_SCHEMA_NAME on the collection element, type attribute, or method argument.

0 if all the type objects to be described are already in the object cache following the first OCIAttrGet() call.

OCIDescribeAny()

1 round-trip to get the REF of the type descriptor object

OCIParamGet()

0


Data Type Mapping and Manipulation Function Round-Trips

Table C-5 lists the number of round-trips for the data type mapping and manipulation functions. The asterisks in the table indicate that all functions with a particular prefix incur the same number of server round-trips. For example, OCINumberAdd(), OCINumberPower(), and OCINumberFromText() all incur zero server round-trips.

Table C-5 Server Round-Trips for Data Type Manipulation Functions

Function Number of Server Round-Trips

OCIColl*()

0; 1 if the collection is not loaded in the cache

OCIDate*()

0

OCIIter*()

0; 1 if the collection is not loaded in the cache

OCINumber*()

0

OCIRaw*()

0

OCIRef*()

0

OCIString*()

0

OCITable*()

0; 1 if the nested table is not loaded in the cache


Any Type and Data Function Round-Trips

Table C-6 lists the number of server round-trips required by Any Type and Data functions. The functions not listed do not generate any round-trips.

Table C-6 Server Round-Trips for Any Type and Data Functions

Function Number of Server Round-Trips

OCIAnyDataAttrGet()

0; 1 if the type information is not loaded in the cache

OCIAnyDataAttrSet()

0; 1 if the type information is not loaded in the cache

OCIAnyDataCollGetElem()

0; 1 if the type information is not loaded in the cache


Other Local Functions

Table C-7 lists the functions that are local and do not require a server round-trip.

Table C-7 Locally Processed Functions

Local Function Name Notes

OCIAttrGet()

When describing an object type, this call makes one round-trip to fetch the type descriptor object.

OCIAttrSet()

 

OCIBindArrayOfStruct()

 

OCIDefineArrayOfStruct()

 

OCIBindByName()

 

OCIBindByPos()

 

OCIBindDynamic()

 

OCIBindObject()

 

OCIDefineByPos()

 

OCIDefineDynamic()

 

OCIDefineObject()

 

OCIDescriptorAlloc()

 

OCIDescriptorFree()

 

OCIEnvCreate()

 

OCIEnvInit()

 

OCIErrorGet()

 

OCIHandleAlloc()

 

OCIHandleFree()

 

OCILdaToSvcCtx()

 

OCIStmtGetBindInfo()

 

OCIStmtPrepare()

 

OCIStmtRelease()

 

OCIStmtPrepare2()

 

OCISvcCtxToLda()