in the clustered index to be smaller than the indexed prefix in secondary
indexes.

row_ext_lookup(): Return NULL if the column is not stored externally.

trx_undo_rec_get_partial_row(): row_build(): Add parameter row_ext_t** ext.

row_build_index_entry(): Add the parameter row_ext_t* ext.
Invoke row_ext_lookup() to fetch prefixes of externally stored columns.

upd_node_t, undo_node_t, purge_node_t: Add the field row_ext_t* ext.

trx-undo_prev_version_build(): Pass offsets==NULL to
rec_set_field_extern_bits().

rec_set_field_extern_bits(), rec_set_field_extern_bits_new():
Accept offsets==NULL.

row_upd_rec_in_place(): Remove the bogus comment that the function
would only be invoked on a clustered index.  Remove the related
debug assertion.

row_upd_rec_in_place(), page_zip_write_rec(): Add parameter "index".

page_dir_set_n_heap(): Add a debug assertion that on compressed
pages, n_heap will always be incremented by one.  Improve code formatting.

page_zip_dir_add_slot(): New function, called from
page_cur_insert_rec_low() after page_mem_alloc_heap().

rec_set_n_owned_new(): Do not call page_zip_rec_set_owned()
on the supremum record.

rec_offs_make_valid(): Add debug assertions.

page_zip_dir_user_size(): Correct an off-by-one error in the debug assertion.

page_zip_apply_log(): Add parameter trx_id_col.  Skip trx_id and roll_ptr.

page_zip_decompress(): Simplify the handling of "storage" in the loop that
copies the uncompressed fields.

page_zip_write_rec(): Store trx_id and roll_ptr separately.

page_zip_write_trx_id(), page_zip_write_roll_ptr(): Fix off-by-one errors.

page_cur_insert_rec_low(): Call page_zip_dir_add_slot() after
page_mem_alloc_heap().  Remove some redundant assertions.
Pass page_zip to page_dir_split_slot().

BLOB pointers, trx_id, and roll_ptr.

btr_empty(), btr_create(), page_create(): Add parameter "index", as some
index information will be encoded on the compressed page.

Define REC_NODE_PTR_SIZE as 4.

Allow btr_page_reorganize() and btr_page_reorganize_low() to fail.

Define the error code DB_ZIP_OVERFLOW.

Make row_ins_index_entry_low() static.

page0zip: Encode the index, log reorganized records, and store uncompressed
fields separately from the compressed data stream.

Initial import of the zip-like compression of B-tree pages.