branches/zip: Fix some BLOB handling bugs.

btr_store_big_rec_extern_fields(): Assert that page_zip is non-NULL
if and only if dict_table_is_zip() holds.

btr_free_externally_stored_field(): Observe dict_table_is_zip().
Allow page_zip==NULL even if dict_table_is_zip().  Remove the
related TODO comment in row_purge_upd_exist_or_extern().

page_zip_available(): uncompressed_size already includes
PAGE_ZIP_DIR_SLOT_SIZE.

page_zip_decompress(): Remove bogus assertion d_stream.next_out == last.
Do not subtract BTR_EXTERN_FIELD_REF_SIZE from d_stream.avail_in when
decompressing records, because the records may be deleted later in
page_zip_apply_log(), and no BLOB pointers are allocated for deleted
records.

btr/btr0cur.c

@@ -3512,6 +3512,7 @@ btr_store_big_rec_extern_fields(
 	space_id = buf_frame_get_space_id(rec);
 
 	page_zip = buf_block_get_page_zip(buf_block_align(rec));
+	ut_a(!dict_table_is_zip(index->table) == !page_zip);
 
 	if (UNIV_LIKELY_NULL(page_zip)) {
 		int	err;
@@ -3847,7 +3848,9 @@ btr_free_externally_stored_field(
 #ifdef UNIV_SYNC_DEBUG
 		buf_page_dbg_add_level(page, SYNC_EXTERN_STORAGE);
 #endif /* UNIV_SYNC_DEBUG */
-		if (UNIV_LIKELY_NULL(page_zip)) {
+		if (dict_table_is_zip(index->table)) {
+			/* Note that page_zip will be NULL
+			in row_purge_upd_exist_or_extern(). */
 			next_page_no = mach_read_from_4(page);
 
 			btr_page_free_low(index->tree, page,
@@ -3859,8 +3862,10 @@ btr_free_externally_stored_field(
 			mlog_write_ulint(field_ref + BTR_EXTERN_LEN + 4,
 						0,
 						MLOG_4BYTES, &mtr);
+			if (page_zip) {
 				page_zip_write_blob_ptr(page_zip,
 						rec, index, offsets, i, &mtr);
+			}
 		} else {
 			ulint	extern_len	= mach_read_from_4(
 					field_ref + BTR_EXTERN_LEN + 4);

include/page0zip.ic

@@ -253,7 +253,7 @@ page_zip_available(
 		Also the BLOB pointers will be allocated from there, but
 		we may as well count them in the length of the record. */
 
-		trailer_len += PAGE_ZIP_DIR_SLOT_SIZE + uncompressed_size;
+		trailer_len += uncompressed_size;
 	}
 
 	return(UNIV_LIKELY(

page/page0zip.c

@@ -1533,11 +1533,10 @@ page_zip_decompress(
 		switch (inflate(&d_stream, Z_SYNC_FLUSH)) {
 		case Z_STREAM_END:
 			/* Apparently, n_dense has grown
-			since the time the page was last compressed. */
-			if (UNIV_UNLIKELY(d_stream.next_out != last)) {
-				/* Somehow, we got a partial record. */
-				goto zlib_error;
-			}
+			since the time the page was last compressed.
+			(d_stream.next_out == last) will not hold,
+			in case the last record was allocated from
+			an originally longer space on the free list. */
 			goto zlib_done;
 		case Z_OK:
 		case Z_BUF_ERROR:
@@ -1645,8 +1644,6 @@ page_zip_decompress(
 						BTR_EXTERN_FIELD_REF_SIZE);
 					d_stream.next_out
 						+= BTR_EXTERN_FIELD_REF_SIZE;
-					d_stream.avail_in
-						-= BTR_EXTERN_FIELD_REF_SIZE;
 				}
 			}