From 81f221828d1689c4c63a036cfa96c389613c29af Mon Sep 17 00:00:00 2001
From: bjyb <1091839467@qq.com>
Date: Sun, 17 Sep 2023 05:39:41 +0800
Subject: [PATCH] Update gin.h

---
 src/include/access/gin.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/include/access/gin.h b/src/include/access/gin.h
index 2fe76b1e0..ab9f21295 100644
--- a/src/include/access/gin.h
+++ b/src/include/access/gin.h
@@ -7,6 +7,17 @@
  *	src/include/access/gin.h
  * --------------------------------------------------------------------------
  */
+
+/*
+GIN(Generalized Inverted Index) is an index structure that stores a set of key, posting list), 
+where the key is a key value and the posting list is a group of locations where the keys have 
+appeared. For example, in ('‘hello', '14:2 23:4 2 23:4'), it means that hello has appeared in the 
+ancestors of 14:2 and 23: 4. In PG, these positions are actually the tid (line number, including 
+data block ID(32bit) and item point(16 bit)) of tuples.
+For each attribute in the table, it may be parsed into multiple key values when establishing 
+the corresponding gin index, so the tid of the same tuple may appear in the posting list of multiple keys.
+*/
+
 #ifndef GIN_H
 #define GIN_H