Changeset 55

Timestamp:

10/02/07 21:26:41 (5 years ago)

Author:

cs186

Message:

add comments

Location:

hw/hw2/postgresql-8.2.4/src

Files:

• backend/access/gist/gistget.c (modified) (2 diffs)
• include/access/gist_private.h (modified) (1 diff)

hw/hw2/postgresql-8.2.4/src/backend/access/gist/gistget.c

@@ -143 +143 @@
 /* insert a new priority queue entry into so->pq */
 static void
-gist_pq_insertpq(GISTScanOpaque so, GISTPQ *newpq)
+gist_pq_insertpq(GISTScanOpaque so, /* State of a GiST scan */
+                 GISTPQ *newpq /* a new GISTPQ entry */
+                 )
 {
   /* CS186 HW2: fill me in! */
@@ -150 +152 @@
 /* 
  * given the current state of the index scan, generate a GISTPQ to insert into
- * the priority queue, and insert it.
+ * the priority queue, and insert it. Note that the "stack" holds the blocks
+ * from the root to the current item.
+ * There are two cases to consider: 
+ *   1) the item being inserted is an entry in a leaf node, identified by a
+ *      block number (from the stack), and the offset.  It points to a data
+ *      item in the database (isdata == true).
+ *   2) the item being inserted is the block number of an index node to 
+ *      be visited next (isdata == false).  The key corresponding to this 
+ *      block number is in the block's *parent* in the tree (which can be
+ *      found in the stack) at the given offset.
  */
 static void

hw/hw2/postgresql-8.2.4/src/include/access/gist_private.h

@@ -56 +56 @@
 typedef struct GISTPQ
 {
-  /* fill me in! */
+  /* CS186 HW2: fill me in! */
 } GISTPQ;