Postgresql内核源码分析-heapam分析

由于篇幅限制，我将提供一个核心函数的简要描述，该函数展示了如何在PostgreSQL中使用堆存储管理器（heapam）进行基本的元组插入操作。

/*
 * heap_insert() -- insert a tuple
 *
 * The new tuple is stamped with the current transaction XID and the
 * specified command ID.
 *
 * After the tuple is inserted, an XLOG INSERT record is logged, unless
 * the new tuple is being inserted in a rerun transaction.  The XLOG record
 * includes the new tuple's XID and CID, as well as info about the relation
 * and a log image of the new tuple.
 *
 * It is assumed that the caller has made provision for any necessary
 * permission checks.
 */
HeapTuple
heap_insert(Relation relation, HeapTuple tup, CommandId cid,
            int options, BulkInsertState bistate)
{
    TransactionId xid = GetCurrentTransactionId();
    HeapTuple    heapTuple;
    Buffer        buffer;
    Buffer        vmbuffer = InvalidBuffer;
    Page        page;
    OffsetNumber offnum;
    ItemId        itemId;
    bool        need_tuple_routine = false;
 
    /*
     * Fill in tuple header fields.
     */
    heapTuple = heap_prepare_insert(relation, tup, xid, cid, options);
 
    /*
     * Find buffer to insert this tuple into.  If the insert is requested to
     * go into the HOT chain, we'll try to put it there.  Otherwise, we
     * always put new tuples at the end of the disk file.
     */
    buffer = RelationGetBufferForTuple(relation, heapTuple,
                                       InvalidBuffer, options,
                                       bistate, &vmbuffer, &offnum);
 
    /*
     * Now, do the actual insertion.
     */
    START_CRIT_SECTION();
 
    RelationPutHeapTuple(relation, buffer, offnum, heapTuple,
                         true /* new tuple */ ,
                         options);
 
    if (vmbuffer != InvalidBuffer)
    {
        /*
         * There is no need to register the buffer for the visibility map
         * here, because we haven't inserted the tuple yet. The visibility
         * map bit will be updated when the transaction commits, as usual.
         */
        ReleaseBuffer(vmbuffer);