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row0sel.c: 

  Add more comments to row_search_for_mysql() and remove the ugly double use of the variable rec in that function


innobase/row/row0sel.c:
  Add more comments to row_search_for_mysql() and remove the ugly double use of the variable rec in that function
parent 652ff87e
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Showing with 49 additions and 29 deletions
innobase/row/row0sel.c
View file @ 582182f8
......@@ -2724,7 +2724,9 @@ row_sel_get_clust_rec_for_mysql(
if (trx->isolation_level > TRX_ISO_READ_UNCOMMITTED
&& !lock_clust_rec_cons_read_sees(clust_rec, clust_index,
*offsets, trx->read_view)) {
/* The following call returns 'offsets' associated with
'old_vers' */
err = row_sel_build_prev_vers_for_mysql(
trx->read_view, clust_index,
prebuilt, clust_rec,
......@@ -3062,7 +3064,7 @@ row_search_for_mysql(
dict_index_t* clust_index;
que_thr_t* thr;
rec_t* rec;
rec_t* index_rec;
rec_t* result_rec;
rec_t* clust_rec;
rec_t* old_vers;
ulint err = DB_SUCCESS;
......@@ -3548,16 +3550,20 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
if (comp) {
next_offs = rec_get_next_offs(rec, TRUE);
if (UNIV_UNLIKELY(next_offs < PAGE_NEW_SUPREMUM)) {
goto wrong_offs;
}
} else {
next_offs = rec_get_next_offs(rec, FALSE);
if (UNIV_UNLIKELY(next_offs < PAGE_OLD_SUPREMUM)) {
goto wrong_offs;
}
}
if (UNIV_UNLIKELY(next_offs >= UNIV_PAGE_SIZE - PAGE_DIR)) {
wrong_offs:
wrong_offs:
if (srv_force_recovery == 0 || moves_up == FALSE) {
ut_print_timestamp(stderr);
buf_page_print(buf_frame_align(rec));
......@@ -3600,6 +3606,9 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
goto next_rec;
}
}
/*-------------------------------------------------------------*/
/* Calculate the 'offsets' associated with 'rec' */
offsets = rec_get_offsets(rec, index, offsets, ULINT_UNDEFINED, &heap);
......@@ -3620,8 +3629,6 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
}
}
/*-------------------------------------------------------------*/
/* Note that we cannot trust the up_match value in the cursor at this
place because we can arrive here after moving the cursor! Thus
we have to recompare rec and search_tuple to determine if they
......@@ -3768,6 +3775,8 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
&& !lock_clust_rec_cons_read_sees(rec, index,
offsets, trx->read_view)) {
/* The following call returns 'offsets'
associated with 'old_vers' */
err = row_sel_build_prev_vers_for_mysql(
trx->read_view, clust_index,
prebuilt, rec,
......@@ -3796,8 +3805,6 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
is necessary, because we can only get the undo
information via the clustered index record. */
/* Get the clustered index record if needed */
index_rec = rec;
ut_ad(index != clust_index);
goto requires_clust_rec;
......@@ -3807,7 +3814,7 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
/* NOTE that at this point rec can be an old version of a clustered
index record built for a consistent read. We cannot assume after this
point that rec is on a buffer pool page. Functions like
page_rec_is_comp() cannot be used then! */
page_rec_is_comp() cannot be used! */
if (UNIV_UNLIKELY(rec_get_deleted_flag(rec, comp))) {
......@@ -3829,19 +3836,15 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
goto next_rec;
}
/* Get the clustered index record if needed and if we did
not do the search using the clustered index */
index_rec = rec;
/* Get the clustered index record if needed, if we did not do the
search using the clustered index. */
if (index != clust_index && prebuilt->need_to_access_clustered) {
requires_clust_rec:
/* Before and after this "if" block, "offsets" will be
related to "rec", which may be in a secondary index "index" or
the clustered index ("clust_index"). However, after this
"if" block, "rec" may be pointing to
"clust_rec" of "clust_index". */
/* We use a 'goto' to the preceding label if a consistent
read of a secondary index record requires us to look up old
versions of the associated clustered index record. */
ut_ad(rec_offs_validate(rec, index, offsets));
......@@ -3849,6 +3852,10 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
clustered index record */
mtr_has_extra_clust_latch = TRUE;
/* The following call returns 'offsets' associated with
'clust_rec'. Note that 'clust_rec' can be an old version
built for a consistent read. */
err = row_sel_get_clust_rec_for_mysql(prebuilt, index, rec,
thr, &clust_rec,
......@@ -3885,17 +3892,26 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
}
if (prebuilt->need_to_access_clustered) {
rec = clust_rec;
result_rec = clust_rec;
ut_ad(rec_offs_validate(rec, clust_index, offsets));
} else {
/* We used 'offsets' for the clust rec, recalculate
them for 'rec' */
offsets = rec_get_offsets(rec, index, offsets,
ULINT_UNDEFINED, &heap);
result_rec = rec;
}
} else {
result_rec = rec;
}
/* We found a qualifying row */
ut_ad(rec_offs_validate(rec,
rec == clust_rec ? clust_index : index,
/* We found a qualifying record 'result_rec'. At this point,
'offsets' are associated with 'result_rec'. */
ut_ad(rec_offs_validate(result_rec,
result_rec != rec ? clust_index : index,
offsets));
if ((match_mode == ROW_SEL_EXACT
......@@ -3916,8 +3932,8 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
not cache rows because there the cursor is a scrollable
cursor. */
row_sel_push_cache_row_for_mysql(prebuilt, rec, offsets);
row_sel_push_cache_row_for_mysql(prebuilt, result_rec,
offsets);
if (prebuilt->n_fetch_cached == MYSQL_FETCH_CACHE_SIZE) {
goto got_row;
......@@ -3926,13 +3942,14 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
goto next_rec;
} else {
if (prebuilt->template_type == ROW_MYSQL_DUMMY_TEMPLATE) {
memcpy(buf + 4, rec - rec_offs_extra_size(offsets),
memcpy(buf + 4, result_rec
- rec_offs_extra_size(offsets),
rec_offs_size(offsets));
mach_write_to_4(buf,
rec_offs_extra_size(offsets) + 4);
} else {
if (!row_sel_store_mysql_rec(buf, prebuilt,
rec, offsets)) {
result_rec, offsets)) {
err = DB_TOO_BIG_RECORD;
goto lock_wait_or_error;
......@@ -3940,15 +3957,18 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
}
if (prebuilt->clust_index_was_generated) {
if (rec != index_rec) {
if (result_rec != rec) {
offsets = rec_get_offsets(
index_rec, index, offsets,
rec, index, offsets,
ULINT_UNDEFINED, &heap);
}
row_sel_store_row_id_to_prebuilt(prebuilt, index_rec,
row_sel_store_row_id_to_prebuilt(prebuilt, rec,
index, offsets);
}
}
/* From this point on, 'offsets' are invalid. */
got_row:
/* We have an optimization to save CPU time: if this is a consistent
read on a unique condition on the clustered index, then we do not
......@@ -3999,7 +4019,7 @@ cursor lock count is done correctly. See bugs #12263 and #12456!
if (moves_up) {
if (UNIV_UNLIKELY(!btr_pcur_move_to_next(pcur, &mtr))) {
not_moved:
not_moved:
btr_pcur_store_position(pcur, &mtr);
if (match_mode != 0) {
......
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