Improve README

Author: ildus

README.md

@@ -1,10 +1,10 @@
 # jsonbc
 
-JSONB compression method for PostgreSQL
+JSONB compression method for PostgreSQL.
 
-## Using
+## Usage
 
-To use it the following patch should be applied to postgresql (git:master):
+To use it the following patch should be applied to PostgreSQL code (git:master):
 
 https://commitfest.postgresql.org/15/1294/
 
@@ -16,3 +16,5 @@ CREATE COMPRESSION METHOD cm1 HANDLER jsonbc_compression_handler;
 CREATE TABLE t(a JSONB);
 ALTER TABLE t ALTER COLUMN a SET COMPRESSED cm1;
 ```
+
+This is very early version and should not be used in any real systems.

jsonbc.c

@@ -207,21 +207,31 @@ jsonbc_compress(AttributeCompression *ac, const struct varlena *data)
 	it = JsonbIteratorInit(&((Jsonb *) data)->root);
 	while ((r = JsonbIteratorNext(&it, &v, false)) != 0)
 	{
-		if (r == WJB_KEY)
+		switch (r)
 		{
-			int					len;
-			int32				key_id;
-			unsigned char	   *ptr = palloc0(6);
+			case WJB_BEGIN_OBJECT:
+				break;
+			case WJB_KEY:
+			{
+				int					len;
+				int32				key_id;
+				unsigned char	   *ptr = palloc0(6);
 
-			Assert(v.type == jbvString);
-			key_id = get_key_id(ac->cmoptoid, v.val.string.val, v.val.string.len);
+				Assert(v.type == jbvString);
+				key_id = get_key_id(ac->cmoptoid, v.val.string.val, v.val.string.len);
 
-			encode_varbyte(key_id, ptr, &len);
-			Assert(len <= 5);
+				encode_varbyte(key_id, ptr, &len);
+				Assert(len <= 5);
 
-			v.type = jbvString;
-			v.val.string.val = (char *) ptr;
-			v.val.string.len = len;
+				v.type = jbvString;
+				v.val.string.val = (char *) ptr;
+				v.val.string.len = len;
+				break;
+			}
+			case WJB_END_OBJECT:
+				break;
+			default:
+				break;
 		}
 		jbv = pushJsonbValue(&state, r, r < WJB_BEGIN_ARRAY ? &v : NULL);
 	}