mach_read_from_4(...) != mach_read_from_4(...) with memcmp(..., ..., 4).

a few places accordingly.

os_aio_simulated_handle(): Add TODO comments about skipping the write
checks for compressed pages.

dict_create_sys_tables_tuple(): Write the compressed page size to
the TYPE column.

open_or_create_data_files(): Simplify the fil_node_create() call.

fil_node_create(): Do not touch space->zip_size.  It was already initialized
by fil_space_create().

fil_reset_too_high_lsns(), buf_flush_buffered_writes(): Add TODO comment
about compressed pages.

buf_flush_init_for_writing(): Handle pages of type FIL_PAGE_INODE,
FIL_PAGE_IBUF_BITMAP, and FIL_PAGE_TYPE_FSP_HDR as uncompressed ones.

page_zip_compress_write_log(): Make static.

page_zip_compress(): Add optional parameter mtr for redo logging.

page_zip_reorganize(): Low-level counterpart of btr_page_reorganize().

page_zip_copy(): Add debug assertions about mtr_memo_contains.

page_cur_insert_rec_low(): Try page_zip_reorganize() and seek to the
new position of insert_rec if it succeeds.

page_copy_rec_list_end(), page_copy_rec_list_start():
Try page_zip_reorganize().

page_move_rec_list_end(): Remove bogus comment.

page_zip_copy(), page_zip_compress_write_log(): Add parameter 'index'.

page_zip_parse_write_header(): Check for !page_zip only if page != NULL.

page_zip_compress_write_log(), page_zip_parse_compress(): Omit some
fields in the page header.  Omit the unused bytes between the modification
log and the page trailer.

parse_or_apply_log_rec_body(): Remove a bogus debug assertion.

page_move_rec_list_start() and page_move_rec_list_end().  Relax the
conditions on insert_will_fit if page_zip is set.

page_delete_rec_list_start(): Make public.

page_zip_copy(): Clear REC_INFO_MIN_REC_FLAG if FIL_PAGE_PREV != FIL_NULL.

set the FIL_PAGE_PREV field of merge_page to FIL_NULL before copying the
records in order not to break the assumption of page_zip_compress() that
min_rec_mark is always set on the first user record of a non-leaf page
whose FIL_PAGE_PREV field is FIL_NULL, and never otherwise.

btr_compress(): Defer any tree modifications until the records
have successfully been copied.

row_purge_remove_sec_if_poss_low(): Simplify the setting of
the return status.

btr_lift_page_up(): If page_copy_rec_list_end() fails, resort to
page_zip_copy().

page_zip_copy(): Validate the copy of the page.

btr_validate_level(): Add missing parameter to added buf_page_print() calls.

btr_root_raise_and_insert(): Replace low-level code with page_zip_copy().

page_zip_copy(): New function to copy the data payload of a compressed page,
byte for byte.  The file page header and trailer are not copied, to avoid
overwriting the fields FIL_PAGE_OFFSET, FIL_PAGE_PREV and FIL_PAGE_NEXT.

btr_cur_compress_if_useful(): Replace if () return(); return() with return.

page_rec_get_next_low(): New function.

page_rec_get_prev(): Invoke page_is_comp() outside the loop.
Replace page_rec_get_next() with loop-specific instances of
page_rec_get_next_low().

page_copy_rec_list_end(): Add some debug assertions.

records have successfully been copied.

make AM_CFLAGS='-std=c89 -Wall -W -pedantic'

btr_root_raise_and_insert(): When copying root to new_page byte for byte,
restore the page number of new_page afterwards.

buf_flush_init_for_writing(): For FIL_PAGE_INDEX, write the page number
and space id also to the uncompressed page.

btr_root_raise_and_insert(): If page_copy_rec_list_end() fails,
copy the pages byte for byte.

page_zip_compress(): Ensure that the uncompressed storage area will
fit on the compressed page.

reorganizing the page fails when compressed pages are enabled.

in CREATE TABLE and ALTER TABLE with AVG_ROW_LENGTH={1,2,4,8,16}.

Introduce FIL_PAGE_ZBLOB_DATA as a synonym for FIL_PAGE_FILE_FLUSH_LSN.

btr_store_big_rec_extern_fields(): Make the assertion about
dict_table_zip_size() more accurate.

buf_LRU_get_free_block(), buf_block_alloc(): Add parameter zip_size.

buf_calc_zblob_page_checksum(): Remove. Replace with page_zip_calc_checksum().

buf_page_init(): Remove parameter zip_size.

buf_page_io_complete(): Add a placeholder for handling compressed pages.

trx_doublewrite_page_inside(): Remove redundant function.

page_zip_write_rec(): Relax an overly tight assertion about blob_no.

buf_page_print(): Print also compressed pages.  Add parameter zip_size.

buf_flush_init_for_writing(): Stamp the fields on a compressed B-tree index
page.

Add the header field FIL_PAGE_ZBLOB_SPACE_ID as an alias of FIL_PAGE_PREV.

page_zip_calc_checksum(): New function.

page_zip_compress(): Avoid copying the fields that are written in
buf_flush_init_for_writing().

page_zip_header_cmp(): New function for comparing those fields of the
page header that will not be written in buf_flush_init_for_writing().

recompressing the page.

buf_flush_init_for_writing(): Calculate the checksum with the actual zip_size.

buf_calc_zblob_page_checksum(): Skip the field FIL_PAGE_SPACE_OR_CHKSUM.

trx_sys_doublewrite_init_or_restore_page(): Use the actual zip_size.

page_cur_insert_rec_low(): If page_zip_alloc() fails, try compressing the
whole page afterwards.

btr_page_reorganize_low(): Rename new_page to temp_page.

btr_store_big_rec_extern_fields(): FIL_PAGE_TYPE is 2 bytes, not 4.

buf_page_init(), buf_page_create(), buf_read_page_low(),
buf_page_init_for_read(): Add parameter zip_size.

buf_page_init_for_backup_restore(),
recv_apply_log_recs_for_backup(): Enclose in #ifdef UNIV_HOTBACKUP.

Enclose some debug code in #ifdef UNIV_LOG_REPLICATE.

page_zip_write_header_log(): Replace page_zip with a pointer to
the uncompressed page.

page_zip_write_rec(): Relax an assertion about blob_no + n_ext.

page_copy_rec_list_to_created_page_write_log(): Allow logging to be disabled.

and to the file space header (FSP_PAGE_ZIP_SIZE, renamed from
FSP_LOWEST_NO_WRITE).

fil_space_struct: Add zip_size.

dict_table_struct: Embed zip_size in flags.

dict_table_zip_size(): Infer zip_size from table->flags.

dict_sys_tables_get_zip_size(): Read zip_size from SYS_TABLES.TYPE.

fil_space_get_zip_size(): Read zip_size from the file space header.

Add the redo log entry type MLOG_ZIP_FILE_CREATE.

page_zip_alloc(): Add parameter "mtr" and log successful calls
to page_zip_compress().

page_zip_write_blob_ptr(), page_zip_write_node_ptr(): Write the offset on
the uncompressed page, because mlog_write_initial_log_record_fast()
does not do so.

page_zip_write_header_log(), page_zip_parse_write_header(): Encode the
offset in one byte.

MLOG_ZIP_LIST_START_COPY and MLOG_ZIP_LIST_END_COPY.

btr_compress(): Simplify a debug assertion.

page_zip_compress_write_log(), page_zip_parse_compress(): New functions.

page_cur_parse_insert_rec(): Simplify the code.

page_parse_create_zip(): Removed.

page_create_zip(), page_copy_rec_list_end(),
page_copy_rec_list_start(): Invoke page_zip_compress_write_log().

btr_page_create(): Remove parameters "prev" and "next".  The pointers
to adjacent B-tree pages will be set in the caller before any user
records are inserted.

Remove the redo log entry type MLOG_ZIP_ROOT_RAISE, since
btr_root_raise_and_insert() will not defer modifications to
the compressed page.

btr_attach_half_pages(): Add parameter new_page_zip.

crash recovery of uncompressed tables.

MLOG_ZIP_COMPRESS and MLOG_ZIP_DECOMPRESS with higher-level entry types.
Implement the logging and crash recovery of MLOG_ZIP_PAGE_CREATE.

page_create_zip(): New function for creating a compressed B-tree page.

page_parse_create_zip(): New function for applying a MLOG_ZIP_PAGE_CREATE
redo log record.

btr_page_create(): Remove the prototype.  Add parameters page_zip, level,
prev, and next.

btr0btr.c: Eliminate page_zip_compress() calls where possible.

page_zip_alloc(), page_zip_compress(), page_zip_decompress(),
page_zip_clear_rec(): Remove parameter mtr.

recv_parse_or_apply_log_rec_body(): Handle MLOG_ZIP_PAGE_CREATE.
Add TODO comments for the other added redo log entry types.

assume that the operation always succeeds.

page_zip_parse_write_blob_ptr(): New function for applying the redo log
record MLOG_ZIP_WRITE_BLOB_PTR.

page_zip_write_blob_ptr(): Write the necessary information to the redo log.

page0zip.c: Tighten the assertions to ensure that blob_ptr < page_zip->n_blobs.

page_zip_write_node_ptr(): Use memcpy() instead of mach_write_to_4().

page_zip_parse_write_header(): New function for applying the redo log of
MLOG_ZIP_WRITE_HEADER.

page_zip_parse_write_node_ptr(): Mark the log corrupted if !page_zip.

page_zip_parse_write_node_ptr(): New function to apply a redo log of
MLOG_ZIP_WRITE_NODE_PTR.

page_zip_write_node_ptr(): Write all needed information to the redo log.

page_zip_write_header_log(): Write all necessary information to the redo log.