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branches/zip: Fix the decompression of deleted records containing externally

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stored columns.

page_zip_decompress(): We indeed need to clear the BLOB pointers of deleted
records twice.  This implies that we also need to invoke rec_get_offsets()
twice for each record on a leaf page.  Add clarifying comments.

page_zip_clear_rec(): Add the flag page_zip_clear_rec_disable for
disabling the clearing of deleted records.
This commit is contained in:
marko 2006-08-04 11:46:20 +00:00
parent 8ebc271948
commit bbcdac2c13
1 changed files with 34 additions and 21 deletions
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55
page/page0zip.c
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@ -1762,12 +1762,19 @@ page_zip_decompress_low(
goto zlib_error;
}
/* Skip the BLOB pointer in case
the record was deleted. The BLOB
pointers will be initialized
(copied from "externs" or cleared)
/* Clear the BLOB pointer in case
the record will be deleted and the
space will not be reused. Note that
the final initialization of the BLOB
pointers (copying from "externs"
or clearing) will have to take place
only after the page modification log
has been applied. */
has been applied. Otherwise, we
could end up with an uninitialized
BLOB pointer when a record is deleted,
reallocated and deleted. */
memset(d_stream.next_out, 0,
BTR_EXTERN_FIELD_REF_SIZE);
d_stream.next_out
+= BTR_EXTERN_FIELD_REF_SIZE;
}
@ -1905,10 +1912,10 @@ err_exit:
ibool exists = !page_zip_dir_find_free(
page_zip, ut_align_offset(
rec, UNIV_PAGE_SIZE));
if (UNIV_UNLIKELY(trx_id_col != ULINT_UNDEFINED)) {
offsets = rec_get_offsets(rec, index, offsets,
ULINT_UNDEFINED, &heap);
offsets = rec_get_offsets(rec, index, offsets,
ULINT_UNDEFINED, &heap);
if (UNIV_UNLIKELY(trx_id_col != ULINT_UNDEFINED)) {
dst = rec_get_nth_field(rec, offsets,
trx_id_col, &len);
ut_ad(len >= DATA_TRX_ID_LEN
@ -1916,21 +1923,12 @@ err_exit:
storage -= DATA_TRX_ID_LEN + DATA_ROLL_PTR_LEN;
memcpy(dst, storage,
DATA_TRX_ID_LEN + DATA_ROLL_PTR_LEN);
if (UNIV_UNLIKELY(!exists)) {
continue;
}
} else if (UNIV_LIKELY(exists)) {
offsets = rec_get_offsets(rec, index, offsets,
ULINT_UNDEFINED, &heap);
} else {
continue;
}
/* Check if there are any externally stored
columns in this existing (not deleted)
record. For each externally stored column,
restore or clear the BTR_EXTERN_FIELD_REF. */
columns in this record. For each externally
stored column, restore or clear the
BTR_EXTERN_FIELD_REF. */
for (i = 0; i < rec_offs_n_fields(offsets); i++) {
if (!rec_offs_nth_extern(offsets, i)) {
@ -1941,6 +1939,8 @@ err_exit:
dst += len - BTR_EXTERN_FIELD_REF_SIZE;
if (UNIV_LIKELY(exists)) {
/* Existing record:
restore the BLOB pointer */
externs -= BTR_EXTERN_FIELD_REF_SIZE;
memcpy(dst, externs,
@ -1948,6 +1948,8 @@ err_exit:
page_zip->n_blobs++;
} else {
/* Deleted record:
clear the BLOB pointer */
memset(dst, 0,
BTR_EXTERN_FIELD_REF_SIZE);
}
@ -2672,6 +2674,13 @@ page_zip_write_trx_id_and_roll_ptr(
memcpy(storage, field, DATA_TRX_ID_LEN + DATA_ROLL_PTR_LEN);
}
#ifdef UNIV_ZIP_DEBUG
/* Set this variable in a debugger to disable page_zip_clear_rec().
The only observable effect should be the compression ratio due to
deleted records not being zeroed out. */
ibool page_zip_clear_rec_disable;
#endif /* UNIV_ZIP_DEBUG */
/**************************************************************************
Clear an area on the uncompressed and compressed page, if possible. */
static
@ -2697,7 +2706,11 @@ page_zip_clear_rec(
heap_no = rec_get_heap_no_new(rec);
ut_ad(heap_no >= 2); /* exclude infimum and supremum */
if (page_zip->m_end
if (
#ifdef UNIV_ZIP_DEBUG
!page_zip_clear_rec_disable &&
#endif /* UNIV_ZIP_DEBUG */
page_zip->m_end
+ 1 + ((heap_no - 1) >= 64)/* size of the log entry */
+ page_zip_get_trailer_len(page_zip, index, NULL)
< page_zip->size) {