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mariadb/storage/innobase/row/row0vers.cc
Marko Mäkelä 3c09f148f3 MDEV-12288 Reset DB_TRX_ID when the history is removed, to speed up MVCC 
Let InnoDB purge reset DB_TRX_ID,DB_ROLL_PTR when the history is removed.

[TODO: It appears that the resetting is not taking place as often as
it could be. We should test that a simple INSERT should eventually
cause row_purge_reset_trx_id() to be invoked unless DROP TABLE is
invoked soon enough.]

The InnoDB clustered index record system columns DB_TRX_ID,DB_ROLL_PTR
are used by multi-versioning. After the history is no longer needed, these
columns can safely be reset to 0 and 1<<55 (to indicate a fresh insert).

When a reader sees 0 in the DB_TRX_ID column, it can instantly determine
that the record is present the read view. There is no need to acquire
the transaction system mutex to check if the transaction exists, because
writes can never be conducted by a transaction whose ID is 0.

The persistent InnoDB undo log used to be split into two parts:
insert_undo and update_undo. The insert_undo log was discarded at
transaction commit or rollback, and the update_undo log was processed
by the purge subsystem. As part of this change, we will only generate
a single undo log for new transactions, and the purge subsystem will
reset the DB_TRX_ID whenever a clustered index record is touched.
That is, all persistent undo log will be preserved at transaction commit
or rollback, to be removed by purge.

The InnoDB redo log format is changed in two ways:
We remove the redo log record type MLOG_UNDO_HDR_REUSE, and
we introduce the MLOG_ZIP_WRITE_TRX_ID record for updating the
DB_TRX_ID,DB_ROLL_PTR in a ROW_FORMAT=COMPRESSED table.

This is also changing the format of persistent InnoDB data files:
undo log and clustered index leaf page records. It will still be
possible via import and export to exchange data files with earlier
versions of MariaDB. The change to clustered index leaf page records
is simple: we allow DB_TRX_ID to be 0.

When it comes to the undo log, we must be able to upgrade from earlier
MariaDB versions after a clean shutdown (no redo log to apply).
While it would be nice to perform a slow shutdown (innodb_fast_shutdown=0)
before an upgrade, to empty the undo logs, we cannot assume that this
has been done. So, separate insert_undo log may exist for recovered
uncommitted transactions. These transactions may be automatically
rolled back, or they may be in XA PREPARE state, in which case InnoDB
will preserve the transaction until an explicit XA COMMIT or XA ROLLBACK.

Upgrade has been tested by starting up MariaDB 10.2 with
./mysql-test-run --manual-gdb innodb.read_only_recovery
and then starting up this patched server with
and without --innodb-read-only.

trx_undo_ptr_t::undo: Renamed from update_undo.

trx_undo_ptr_t::old_insert: Renamed from insert_undo.

trx_rseg_t::undo_list: Renamed from update_undo_list.

trx_rseg_t::undo_cached: Merged from update_undo_cached
and insert_undo_cached.

trx_rseg_t::old_insert_list: Renamed from insert_undo_list.

row_purge_reset_trx_id(): New function to reset the columns.
This will be called for all undo processing in purge
that does not remove the clustered index record.

trx_undo_update_rec_get_update(): Allow trx_id=0 when copying the
old DB_TRX_ID of the record to the undo log.

ReadView::changes_visible(): Allow id==0. (Return true for it.
This is what speeds up the MVCC.)

row_vers_impl_x_locked_low(), row_vers_build_for_semi_consistent_read():
Implement a fast path for DB_TRX_ID=0.

Always initialize the TRX_UNDO_PAGE_TYPE to 0. Remove undo->type.

MLOG_UNDO_HDR_REUSE: Remove. This changes the redo log format!

innobase_start_or_create_for_mysql(): Set srv_undo_sources before
starting any transactions.

The parsing of the MLOG_ZIP_WRITE_TRX_ID record was successfully
tested by running the following:
./mtr --parallel=auto --mysqld=--debug=d,ib_log innodb_zip.bug56680
grep MLOG_ZIP_WRITE_TRX_ID var/*/log/mysqld.1.err
2017-07-07 13:08:48 +03:00

1380 lines
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/*****************************************************************************
Copyright (c) 1997, 2016, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2017, MariaDB Corporation
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
*****************************************************************************/
/**************************************************//**
@file row/row0vers.cc
Row versions
Created 2/6/1997 Heikki Tuuri
*******************************************************/
#include "ha_prototypes.h"
#include "row0vers.h"
#include "dict0dict.h"
#include "dict0boot.h"
#include "btr0btr.h"
#include "mach0data.h"
#include "trx0rseg.h"
#include "trx0trx.h"
#include "trx0roll.h"
#include "trx0undo.h"
#include "trx0purge.h"
#include "trx0rec.h"
#include "que0que.h"
#include "row0row.h"
#include "row0upd.h"
#include "rem0cmp.h"
#include "read0read.h"
#include "lock0lock.h"
#include "row0mysql.h"
/** Check whether all non-virtual columns in a virtual index match that of in
the cluster index
@param[in] index the secondary index
@param[in] row the cluster index row in dtuple form
@param[in] ext externally stored column prefix or NULL
@param[in] ientry the secondary index entry
@param[in,out] heap heap used to build virtual dtuple
@param[in,out] n_non_v_col number of non-virtual columns in the index
@return true if all matches, false otherwise */
static
bool
row_vers_non_vc_match(
dict_index_t* index,
const dtuple_t* row,
const row_ext_t* ext,
const dtuple_t* ientry,
mem_heap_t* heap,
ulint* n_non_v_col);
/*****************************************************************//**
Finds out if an active transaction has inserted or modified a secondary
index record.
@return 0 if committed, else the active transaction id;
NOTE that this function can return false positives but never false
negatives. The caller must confirm all positive results by calling
trx_is_active() while holding lock_sys->mutex. */
UNIV_INLINE
trx_t*
row_vers_impl_x_locked_low(
/*=======================*/
const rec_t* clust_rec, /*!< in: clustered index record */
dict_index_t* clust_index, /*!< in: the clustered index */
const rec_t* rec, /*!< in: secondary index record */
dict_index_t* index, /*!< in: the secondary index */
const ulint* offsets, /*!< in: rec_get_offsets(rec, index) */
mtr_t* mtr) /*!< in/out: mini-transaction */
{
trx_id_t trx_id;
ibool corrupt;
ulint comp;
ulint rec_del;
const rec_t* version;
rec_t* prev_version = NULL;
ulint* clust_offsets;
mem_heap_t* heap;
dtuple_t* ientry = NULL;
mem_heap_t* v_heap = NULL;
const dtuple_t* cur_vrow = NULL;
DBUG_ENTER("row_vers_impl_x_locked_low");
ut_ad(rec_offs_validate(rec, index, offsets));
if (ulint trx_id_offset = clust_index->trx_id_offset) {
trx_id = mach_read_from_6(clust_rec + trx_id_offset);
if (trx_id == 0) {
/* The transaction history was already purged. */
DBUG_RETURN(0);
}
}
heap = mem_heap_create(1024);
clust_offsets = rec_get_offsets(
clust_rec, clust_index, NULL, ULINT_UNDEFINED, &heap);
trx_id = row_get_rec_trx_id(clust_rec, clust_index, clust_offsets);
if (trx_id == 0) {
/* The transaction history was already purged. */
mem_heap_free(heap);
DBUG_RETURN(0);
}
corrupt = FALSE;
trx_t* trx = trx_rw_is_active(trx_id, &corrupt, true);
if (trx == 0) {
/* The transaction that modified or inserted clust_rec is no
longer active, or it is corrupt: no implicit lock on rec */
if (corrupt) {
lock_report_trx_id_insanity(
trx_id, clust_rec, clust_index, clust_offsets,
trx_sys_get_max_trx_id());
}
mem_heap_free(heap);
DBUG_RETURN(0);
}
comp = page_rec_is_comp(rec);
ut_ad(index->table == clust_index->table);
ut_ad(!!comp == dict_table_is_comp(index->table));
ut_ad(!comp == !page_rec_is_comp(clust_rec));
rec_del = rec_get_deleted_flag(rec, comp);
if (dict_index_has_virtual(index)) {
ulint n_ext;
ulint est_size = DTUPLE_EST_ALLOC(index->n_fields);
/* Allocate the dtuple for virtual columns extracted from undo
log with its own heap, so to avoid it being freed as we
iterating in the version loop below. */
v_heap = mem_heap_create(est_size);
ientry = row_rec_to_index_entry(
rec, index, offsets, &n_ext, v_heap);
}
/* We look up if some earlier version, which was modified by
the trx_id transaction, of the clustered index record would
require rec to be in a different state (delete marked or
unmarked, or have different field values, or not existing). If
there is such a version, then rec was modified by the trx_id
transaction, and it has an implicit x-lock on rec. Note that
if clust_rec itself would require rec to be in a different
state, then the trx_id transaction has not yet had time to
modify rec, and does not necessarily have an implicit x-lock
on rec. */
for (version = clust_rec;; version = prev_version) {
row_ext_t* ext;
dtuple_t* row;
dtuple_t* entry;
ulint vers_del;
trx_id_t prev_trx_id;
mem_heap_t* old_heap = heap;
const dtuple_t* vrow = NULL;
/* We keep the semaphore in mtr on the clust_rec page, so
that no other transaction can update it and get an
implicit x-lock on rec until mtr_commit(mtr). */
heap = mem_heap_create(1024);
trx_undo_prev_version_build(
clust_rec, mtr, version, clust_index, clust_offsets,
heap, &prev_version, NULL,
dict_index_has_virtual(index) ? &vrow : NULL, 0);
/* The oldest visible clustered index version must not be
delete-marked, because we never start a transaction by
inserting a delete-marked record. */
ut_ad(prev_version
|| !rec_get_deleted_flag(version, comp)
|| !trx_rw_is_active(trx_id, NULL, false));
/* Free version and clust_offsets. */
mem_heap_free(old_heap);
if (prev_version == NULL) {
/* We reached the oldest visible version without
finding an older version of clust_rec that would
match the secondary index record. If the secondary
index record is not delete marked, then clust_rec
is considered the correct match of the secondary
index record and hence holds the implicit lock. */
if (rec_del) {
/* The secondary index record is del marked.
So, the implicit lock holder of clust_rec
did not modify the secondary index record yet,
and is not holding an implicit lock on it.
This assumes that whenever a row is inserted
or updated, the leaf page record always is
created with a clear delete-mark flag.
(We never insert a delete-marked record.) */
trx_release_reference(trx);
trx = 0;
}
break;
}
clust_offsets = rec_get_offsets(
prev_version, clust_index, NULL, ULINT_UNDEFINED,
&heap);
vers_del = rec_get_deleted_flag(prev_version, comp);
prev_trx_id = row_get_rec_trx_id(prev_version, clust_index,
clust_offsets);
/* The stack of versions is locked by mtr. Thus, it
is safe to fetch the prefixes for externally stored
columns. */
row = row_build(ROW_COPY_POINTERS, clust_index, prev_version,
clust_offsets,
NULL, NULL, NULL, &ext, heap);
if (dict_index_has_virtual(index)) {
if (vrow) {
/* Keep the virtual row info for the next
version */
cur_vrow = dtuple_copy(vrow, v_heap);
dtuple_dup_v_fld(cur_vrow, v_heap);
}
if (!cur_vrow) {
ulint n_non_v_col = 0;
/* If the indexed virtual columns has changed,
there must be log record to generate vrow.
Otherwise, it is not changed, so no need
to compare */
if (row_vers_non_vc_match(
index, row, ext, ientry, heap,
&n_non_v_col) == 0) {
if (rec_del != vers_del) {
break;
}
} else if (!rec_del) {
break;
}
goto result_check;
} else {
ut_ad(row->n_v_fields == cur_vrow->n_v_fields);
dtuple_copy_v_fields(row, cur_vrow);
}
}
entry = row_build_index_entry(row, ext, index, heap);
/* entry may be NULL if a record was inserted in place
of a deleted record, and the BLOB pointers of the new
record were not initialized yet. But in that case,
prev_version should be NULL. */
ut_a(entry != NULL);
/* If we get here, we know that the trx_id transaction
modified prev_version. Let us check if prev_version
would require rec to be in a different state. */
/* The previous version of clust_rec must be
accessible, because clust_rec was not a fresh insert.
There is no guarantee that the transaction is still
active. */
/* We check if entry and rec are identified in the alphabetical
ordering */
if (0 == cmp_dtuple_rec(entry, rec, offsets)) {
/* The delete marks of rec and prev_version should be
equal for rec to be in the state required by
prev_version */
if (rec_del != vers_del) {
break;
}
/* It is possible that the row was updated so that the
secondary index record remained the same in
alphabetical ordering, but the field values changed
still. For example, 'abc' -> 'ABC'. Check also that. */
dtuple_set_types_binary(
entry, dtuple_get_n_fields(entry));
if (0 != cmp_dtuple_rec(entry, rec, offsets)) {
break;
}
} else if (!rec_del) {
/* The delete mark should be set in rec for it to be
in the state required by prev_version */
break;
}
result_check:
if (trx->id != prev_trx_id) {
/* prev_version was the first version modified by
the trx_id transaction: no implicit x-lock */
trx_release_reference(trx);
trx = 0;
break;
}
}
DBUG_PRINT("info", ("Implicit lock is held by trx:" TRX_ID_FMT, trx_id));
if (v_heap != NULL) {
mem_heap_free(v_heap);
}
mem_heap_free(heap);
DBUG_RETURN(trx);
}
/*****************************************************************//**
Finds out if an active transaction has inserted or modified a secondary
index record.
@return 0 if committed, else the active transaction id;
NOTE that this function can return false positives but never false
negatives. The caller must confirm all positive results by calling
trx_is_active() while holding lock_sys->mutex. */
trx_t*
row_vers_impl_x_locked(
/*===================*/
const rec_t* rec, /*!< in: record in a secondary index */
dict_index_t* index, /*!< in: the secondary index */
const ulint* offsets)/*!< in: rec_get_offsets(rec, index) */
{
mtr_t mtr;
trx_t* trx;
const rec_t* clust_rec;
dict_index_t* clust_index;
ut_ad(!lock_mutex_own());
ut_ad(!trx_sys_mutex_own());
mtr_start(&mtr);
/* Search for the clustered index record. The latch on the
page of clust_rec locks the top of the stack of versions. The
bottom of the version stack is not locked; oldest versions may
disappear by the fact that transactions may be committed and
collected by the purge. This is not a problem, because we are
only interested in active transactions. */
clust_rec = row_get_clust_rec(
BTR_SEARCH_LEAF, rec, index, &clust_index, &mtr);
if (!clust_rec) {
/* In a rare case it is possible that no clust rec is found
for a secondary index record: if in row0umod.cc
row_undo_mod_remove_clust_low() we have already removed the
clust rec, while purge is still cleaning and removing
secondary index records associated with earlier versions of
the clustered index record. In that case there cannot be
any implicit lock on the secondary index record, because
an active transaction which has modified the secondary index
record has also modified the clustered index record. And in
a rollback we always undo the modifications to secondary index
records before the clustered index record. */
trx = 0;
} else {
trx = row_vers_impl_x_locked_low(
clust_rec, clust_index, rec, index, offsets, &mtr);
ut_ad(trx == 0 || trx_is_referenced(trx));
}
mtr_commit(&mtr);
return(trx);
}
/*****************************************************************//**
Finds out if we must preserve a delete marked earlier version of a clustered
index record, because it is >= the purge view.
@param[in] trx_id transaction id in the version
@param[in] name table name
@param[in,out] mtr mini transaction holding the latch on the
clustered index record; it will also hold
the latch on purge_view
@return TRUE if earlier version should be preserved */
ibool
row_vers_must_preserve_del_marked(
/*==============================*/
trx_id_t trx_id,
const table_name_t& name,
mtr_t* mtr)
{
ut_ad(!rw_lock_own(&(purge_sys->latch), RW_LOCK_S));
mtr_s_lock(&purge_sys->latch, mtr);
return(!purge_sys->view.changes_visible(trx_id, name));
}
/** Check whether all non-virtual columns in a virtual index match that of in
the cluster index
@param[in] index the secondary index
@param[in] row the cluster index row in dtuple form
@param[in] ext externally stored column prefix or NULL
@param[in] ientry the secondary index entry
@param[in,out] heap heap used to build virtual dtuple
@param[in,out] n_non_v_col number of non-virtual columns in the index
@return true if all matches, false otherwise */
static
bool
row_vers_non_vc_match(
dict_index_t* index,
const dtuple_t* row,
const row_ext_t* ext,
const dtuple_t* ientry,
mem_heap_t* heap,
ulint* n_non_v_col)
{
const dfield_t* field1;
dfield_t* field2;
ulint n_fields = dtuple_get_n_fields(ientry);
ulint ret = true;
*n_non_v_col = 0;
/* Build index entry out of row */
dtuple_t* nentry = row_build_index_entry(row, ext, index, heap);
for (ulint i = 0; i < n_fields; i++) {
const dict_field_t* ind_field = dict_index_get_nth_field(
index, i);
const dict_col_t* col = ind_field->col;
/* Only check non-virtual columns */
if (dict_col_is_virtual(col)) {
continue;
}
if (ret) {
field1 = dtuple_get_nth_field(ientry, i);
field2 = dtuple_get_nth_field(nentry, i);
if (cmp_dfield_dfield(field1, field2) != 0) {
ret = false;
}
}
(*n_non_v_col)++;
}
return(ret);
}
/** build virtual column value from current cluster index record data
@param[in,out] row the cluster index row in dtuple form
@param[in] clust_index clustered index
@param[in] index the secondary index
@param[in] heap heap used to build virtual dtuple */
static
void
row_vers_build_clust_v_col(
dtuple_t* row,
dict_index_t* clust_index,
dict_index_t* index,
mem_heap_t* heap)
{
mem_heap_t* local_heap = NULL;
for (ulint i = 0; i < dict_index_get_n_fields(index); i++) {
const dict_field_t* ind_field = dict_index_get_nth_field(
index, i);
if (dict_col_is_virtual(ind_field->col)) {
const dict_v_col_t* col;
col = reinterpret_cast<const dict_v_col_t*>(
ind_field->col);
innobase_get_computed_value(
row, col, clust_index, &local_heap,
heap, NULL, current_thd, NULL, NULL,
NULL, NULL);
}
}
if (local_heap) {
mem_heap_free(local_heap);
}
}
/** Build latest virtual column data from undo log
@param[in] in_purge whether this is the purge thread
@param[in] rec clustered index record
@param[in] clust_index clustered index
@param[in,out] clust_offsets offsets on the clustered index record
@param[in] index the secondary index
@param[in] roll_ptr the rollback pointer for the purging record
@param[in] trx_id trx id for the purging record
@param[in,out] v_heap heap used to build vrow
@param[out] v_row dtuple holding the virtual rows
@param[in,out] mtr mtr holding the latch on rec */
static
void
row_vers_build_cur_vrow_low(
bool in_purge,
const rec_t* rec,
dict_index_t* clust_index,
ulint* clust_offsets,
dict_index_t* index,
roll_ptr_t roll_ptr,
trx_id_t trx_id,
mem_heap_t* v_heap,
const dtuple_t**vrow,
mtr_t* mtr)
{
const rec_t* version;
rec_t* prev_version;
mem_heap_t* heap = NULL;
ulint num_v = dict_table_get_n_v_cols(index->table);
const dfield_t* field;
ulint i;
bool all_filled = false;
*vrow = dtuple_create_with_vcol(v_heap, 0, num_v);
dtuple_init_v_fld(*vrow);
for (i = 0; i < num_v; i++) {
dfield_get_type(dtuple_get_nth_v_field(*vrow, i))->mtype
= DATA_MISSING;
}
version = rec;
/* If this is called by purge thread, set TRX_UNDO_PREV_IN_PURGE
bit to search the undo log until we hit the current undo log with
roll_ptr */
const ulint status = in_purge
? TRX_UNDO_PREV_IN_PURGE | TRX_UNDO_GET_OLD_V_VALUE
: TRX_UNDO_GET_OLD_V_VALUE;
while (!all_filled) {
mem_heap_t* heap2 = heap;
heap = mem_heap_create(1024);
roll_ptr_t cur_roll_ptr = row_get_rec_roll_ptr(
version, clust_index, clust_offsets);
trx_undo_prev_version_build(
rec, mtr, version, clust_index, clust_offsets,
heap, &prev_version, NULL, vrow, status);
if (heap2) {
mem_heap_free(heap2);
}
if (!prev_version) {
/* Versions end here */
break;
}
clust_offsets = rec_get_offsets(prev_version, clust_index,
NULL, ULINT_UNDEFINED, &heap);
ulint entry_len = dict_index_get_n_fields(index);
all_filled = true;
for (i = 0; i < entry_len; i++) {
const dict_field_t* ind_field
= dict_index_get_nth_field(index, i);
const dict_col_t* col = ind_field->col;
if (!dict_col_is_virtual(col)) {
continue;
}
const dict_v_col_t* v_col
= reinterpret_cast<const dict_v_col_t*>(col);
field = dtuple_get_nth_v_field(*vrow, v_col->v_pos);
if (dfield_get_type(field)->mtype == DATA_MISSING) {
all_filled = false;
break;
}
}
trx_id_t rec_trx_id = row_get_rec_trx_id(
prev_version, clust_index, clust_offsets);
if (rec_trx_id < trx_id || roll_ptr == cur_roll_ptr) {
break;
}
version = prev_version;
}
mem_heap_free(heap);
}
/** Check a virtual column value index secondary virtual index matches
that of current cluster index record, which is recreated from information
stored in undo log
@param[in] in_purge called by purge thread
@param[in] rec record in the clustered index
@param[in] row the cluster index row in dtuple form
@param[in] ext externally stored column prefix or NULL
@param[in] clust_index cluster index
@param[in] clust_offsets offsets on the cluster record
@param[in] index the secondary index
@param[in] ientry the secondary index entry
@param[in] roll_ptr the rollback pointer for the purging record
@param[in] trx_id trx id for the purging record
@param[in,out] v_heap heap used to build virtual dtuple
@param[in,out] v_row dtuple holding the virtual rows (if needed)
@param[in] mtr mtr holding the latch on rec
@return true if matches, false otherwise */
static
bool
row_vers_vc_matches_cluster(
bool in_purge,
const rec_t* rec,
const dtuple_t* row,
row_ext_t* ext,
dict_index_t* clust_index,
ulint* clust_offsets,
dict_index_t* index,
const dtuple_t* ientry,
roll_ptr_t roll_ptr,
trx_id_t trx_id,
mem_heap_t* v_heap,
const dtuple_t**vrow,
mtr_t* mtr)
{
const rec_t* version;
rec_t* prev_version;
mem_heap_t* heap2;
mem_heap_t* heap = NULL;
mem_heap_t* tuple_heap;
ulint num_v = dict_table_get_n_v_cols(index->table);
bool compare[REC_MAX_N_FIELDS];
ulint n_fields = dtuple_get_n_fields(ientry);
ulint n_non_v_col = 0;
ulint n_cmp_v_col = 0;
const dfield_t* field1;
dfield_t* field2;
ulint i;
tuple_heap = mem_heap_create(1024);
/* First compare non-virtual columns (primary keys) */
if (!row_vers_non_vc_match(index, row, ext, ientry, tuple_heap,
&n_non_v_col)) {
mem_heap_free(tuple_heap);
return(false);
}
ut_ad(n_fields > n_non_v_col);
*vrow = dtuple_create_with_vcol(v_heap ? v_heap : tuple_heap, 0, num_v);
dtuple_init_v_fld(*vrow);
for (i = 0; i < num_v; i++) {
dfield_get_type(dtuple_get_nth_v_field(*vrow, i))->mtype
= DATA_MISSING;
compare[i] = false;
}
version = rec;
/* If this is called by purge thread, set TRX_UNDO_PREV_IN_PURGE
bit to search the undo log until we hit the current undo log with
roll_ptr */
ulint status = (in_purge ? TRX_UNDO_PREV_IN_PURGE : 0)
| TRX_UNDO_GET_OLD_V_VALUE;
while (n_cmp_v_col < n_fields - n_non_v_col) {
heap2 = heap;
heap = mem_heap_create(1024);
roll_ptr_t cur_roll_ptr = row_get_rec_roll_ptr(
version, clust_index, clust_offsets);
ut_ad(cur_roll_ptr != 0);
ut_ad(in_purge == (roll_ptr != 0));
trx_undo_prev_version_build(
rec, mtr, version, clust_index, clust_offsets,
heap, &prev_version, NULL, vrow, status);
if (heap2) {
mem_heap_free(heap2);
}
if (!prev_version) {
/* Versions end here */
goto func_exit;
}
clust_offsets = rec_get_offsets(prev_version, clust_index,
NULL, ULINT_UNDEFINED, &heap);
ulint entry_len = dict_index_get_n_fields(index);
for (i = 0; i < entry_len; i++) {
const dict_field_t* ind_field
= dict_index_get_nth_field(index, i);
const dict_col_t* col = ind_field->col;
field1 = dtuple_get_nth_field(ientry, i);
if (!dict_col_is_virtual(col)) {
continue;
}
const dict_v_col_t* v_col
= reinterpret_cast<const dict_v_col_t*>(col);
field2
= dtuple_get_nth_v_field(*vrow, v_col->v_pos);
if ((dfield_get_type(field2)->mtype != DATA_MISSING)
&& (!compare[v_col->v_pos])) {
if (ind_field->prefix_len != 0
&& !dfield_is_null(field2)
&& field2->len > ind_field->prefix_len) {
field2->len = ind_field->prefix_len;
}
/* The index field mismatch */
if (v_heap
|| cmp_dfield_dfield(field2, field1) != 0) {
if (v_heap) {
dtuple_dup_v_fld(*vrow, v_heap);
}
mem_heap_free(tuple_heap);
mem_heap_free(heap);
return(false);
}
compare[v_col->v_pos] = true;
n_cmp_v_col++;
}
}
trx_id_t rec_trx_id = row_get_rec_trx_id(
prev_version, clust_index, clust_offsets);
if (rec_trx_id < trx_id || roll_ptr == cur_roll_ptr) {
break;
}
version = prev_version;
}
func_exit:
if (n_cmp_v_col == 0) {
*vrow = NULL;
}
mem_heap_free(tuple_heap);
mem_heap_free(heap);
/* FIXME: In the case of n_cmp_v_col is not the same as
n_fields - n_non_v_col, callback is needed to compare the rest
columns. At the timebeing, we will need to return true */
return (true);
}
/** Build a dtuple contains virtual column data for current cluster index
@param[in] in_purge called by purge thread
@param[in] rec cluster index rec
@param[in] clust_index cluster index
@param[in] clust_offsets cluster rec offset
@param[in] index secondary index
@param[in] ientry secondary index rec
@param[in] roll_ptr roll_ptr for the purge record
@param[in] trx_id transaction ID on the purging record
@param[in,out] heap heap memory
@param[in,out] v_heap heap memory to keep virtual colum dtuple
@param[in] mtr mtr holding the latch on rec
@return dtuple contains virtual column data */
static
const dtuple_t*
row_vers_build_cur_vrow(
bool in_purge,
const rec_t* rec,
dict_index_t* clust_index,
ulint** clust_offsets,
dict_index_t* index,
const dtuple_t* ientry,
roll_ptr_t roll_ptr,
trx_id_t trx_id,
mem_heap_t* heap,
mem_heap_t* v_heap,
mtr_t* mtr)
{
const dtuple_t* cur_vrow = NULL;
roll_ptr_t t_roll_ptr = row_get_rec_roll_ptr(
rec, clust_index, *clust_offsets);
/* if the row is newly inserted, then the virtual
columns need to be computed */
if (trx_undo_roll_ptr_is_insert(t_roll_ptr)) {
ut_ad(!rec_get_deleted_flag(rec, page_rec_is_comp(rec)));
/* This is a newly inserted record and cannot
be deleted, So the externally stored field
cannot be freed yet. */
dtuple_t* row = row_build(ROW_COPY_POINTERS, clust_index,
rec, *clust_offsets,
NULL, NULL, NULL, NULL, heap);
row_vers_build_clust_v_col(
row, clust_index, index, heap);
cur_vrow = dtuple_copy(row, v_heap);
dtuple_dup_v_fld(cur_vrow, v_heap);
} else {
/* Try to fetch virtual column data from undo log */
row_vers_build_cur_vrow_low(
in_purge, rec, clust_index, *clust_offsets,
index, roll_ptr, trx_id, v_heap, &cur_vrow, mtr);
}
*clust_offsets = rec_get_offsets(rec, clust_index, NULL,
ULINT_UNDEFINED, &heap);
return(cur_vrow);
}
/*****************************************************************//**
Finds out if a version of the record, where the version >= the current
purge view, should have ientry as its secondary index entry. We check
if there is any not delete marked version of the record where the trx
id >= purge view, and the secondary index entry and ientry are identified in
the alphabetical ordering; exactly in this case we return TRUE.
@return TRUE if earlier version should have */
ibool
row_vers_old_has_index_entry(
/*=========================*/
ibool also_curr,/*!< in: TRUE if also rec is included in the
versions to search; otherwise only versions
prior to it are searched */
const rec_t* rec, /*!< in: record in the clustered index; the
caller must have a latch on the page */
mtr_t* mtr, /*!< in: mtr holding the latch on rec; it will
also hold the latch on purge_view */
dict_index_t* index, /*!< in: the secondary index */
const dtuple_t* ientry, /*!< in: the secondary index entry */
roll_ptr_t roll_ptr,/*!< in: roll_ptr for the purge record */
trx_id_t trx_id) /*!< in: transaction ID on the purging record */
{
const rec_t* version;
rec_t* prev_version;
dict_index_t* clust_index;
ulint* clust_offsets;
mem_heap_t* heap;
mem_heap_t* heap2;
dtuple_t* row;
const dtuple_t* entry;
ulint comp;
const dtuple_t* vrow = NULL;
mem_heap_t* v_heap = NULL;
const dtuple_t* cur_vrow = NULL;
ut_ad(mtr_memo_contains_page_flagged(mtr, rec, MTR_MEMO_PAGE_X_FIX
| MTR_MEMO_PAGE_S_FIX));
ut_ad(!rw_lock_own(&(purge_sys->latch), RW_LOCK_S));
clust_index = dict_table_get_first_index(index->table);
comp = page_rec_is_comp(rec);
ut_ad(!dict_table_is_comp(index->table) == !comp);
heap = mem_heap_create(1024);
clust_offsets = rec_get_offsets(rec, clust_index, NULL,
ULINT_UNDEFINED, &heap);
if (dict_index_has_virtual(index)) {
v_heap = mem_heap_create(100);
}
DBUG_EXECUTE_IF("ib_purge_virtual_index_crash",
DBUG_SUICIDE(););
if (also_curr && !rec_get_deleted_flag(rec, comp)) {
row_ext_t* ext;
/* The top of the stack of versions is locked by the
mtr holding a latch on the page containing the
clustered index record. The bottom of the stack is
locked by the fact that the purge_sys->view must
'overtake' any read view of an active transaction.
Thus, it is safe to fetch the prefixes for
externally stored columns. */
row = row_build(ROW_COPY_POINTERS, clust_index,
rec, clust_offsets,
NULL, NULL, NULL, &ext, heap);
if (dict_index_has_virtual(index)) {
#ifdef DBUG_OFF
# define dbug_v_purge false
#else /* DBUG_OFF */
bool dbug_v_purge = false;
#endif /* DBUG_OFF */
DBUG_EXECUTE_IF(
"ib_purge_virtual_index_callback",
dbug_v_purge = true;);
roll_ptr_t t_roll_ptr = row_get_rec_roll_ptr(
rec, clust_index, clust_offsets);
/* if the row is newly inserted, then the virtual
columns need to be computed */
if (trx_undo_roll_ptr_is_insert(t_roll_ptr)
|| dbug_v_purge) {
row_vers_build_clust_v_col(
row, clust_index, index, heap);
entry = row_build_index_entry(
row, ext, index, heap);
if (entry && !dtuple_coll_cmp(ientry, entry)) {
mem_heap_free(heap);
if (v_heap) {
mem_heap_free(v_heap);
}
return(TRUE);
}
} else {
if (row_vers_vc_matches_cluster(
also_curr, rec, row, ext, clust_index,
clust_offsets, index, ientry, roll_ptr,
trx_id, NULL, &vrow, mtr)) {
mem_heap_free(heap);
if (v_heap) {
mem_heap_free(v_heap);
}
return(TRUE);
}
}
clust_offsets = rec_get_offsets(rec, clust_index, NULL,
ULINT_UNDEFINED, &heap);
} else {
entry = row_build_index_entry(
row, ext, index, heap);
/* If entry == NULL, the record contains unset BLOB
pointers. This must be a freshly inserted record. If
this is called from
row_purge_remove_sec_if_poss_low(), the thread will
hold latches on the clustered index and the secondary
index. Because the insert works in three steps:
(1) insert the record to clustered index
(2) store the BLOBs and update BLOB pointers
(3) insert records to secondary indexes
the purge thread can safely ignore freshly inserted
records and delete the secondary index record. The
thread that inserted the new record will be inserting
the secondary index records. */
/* NOTE that we cannot do the comparison as binary
fields because the row is maybe being modified so that
the clustered index record has already been updated to
a different binary value in a char field, but the
collation identifies the old and new value anyway! */
if (entry && !dtuple_coll_cmp(ientry, entry)) {
mem_heap_free(heap);
if (v_heap) {
mem_heap_free(v_heap);
}
return(TRUE);
}
}
} else if (dict_index_has_virtual(index)) {
/* The current cluster index record could be
deleted, but the previous version of it might not. We will
need to get the virtual column data from undo record
associated with current cluster index */
cur_vrow = row_vers_build_cur_vrow(
also_curr, rec, clust_index, &clust_offsets,
index, ientry, roll_ptr, trx_id, heap, v_heap, mtr);
}
version = rec;
for (;;) {
heap2 = heap;
heap = mem_heap_create(1024);
vrow = NULL;
trx_undo_prev_version_build(rec, mtr, version,
clust_index, clust_offsets,
heap, &prev_version, NULL,
dict_index_has_virtual(index)
? &vrow : NULL, 0);
mem_heap_free(heap2); /* free version and clust_offsets */
if (!prev_version) {
/* Versions end here */
mem_heap_free(heap);
if (v_heap) {
mem_heap_free(v_heap);
}
return(FALSE);
}
clust_offsets = rec_get_offsets(prev_version, clust_index,
NULL, ULINT_UNDEFINED, &heap);
if (dict_index_has_virtual(index)) {
if (vrow) {
/* Keep the virtual row info for the next
version, unless it is changed */
mem_heap_empty(v_heap);
cur_vrow = dtuple_copy(vrow, v_heap);
dtuple_dup_v_fld(cur_vrow, v_heap);
}
if (!cur_vrow) {
/* Nothing for this index has changed,
continue */
version = prev_version;
continue;
}
}
if (!rec_get_deleted_flag(prev_version, comp)) {
row_ext_t* ext;
/* The stack of versions is locked by mtr.
Thus, it is safe to fetch the prefixes for
externally stored columns. */
row = row_build(ROW_COPY_POINTERS, clust_index,
prev_version, clust_offsets,
NULL, NULL, NULL, &ext, heap);
if (dict_index_has_virtual(index)) {
ut_ad(cur_vrow);
ut_ad(row->n_v_fields == cur_vrow->n_v_fields);
dtuple_copy_v_fields(row, cur_vrow);
}
entry = row_build_index_entry(row, ext, index, heap);
/* If entry == NULL, the record contains unset
BLOB pointers. This must be a freshly
inserted record that we can safely ignore.
For the justification, see the comments after
the previous row_build_index_entry() call. */
/* NOTE that we cannot do the comparison as binary
fields because maybe the secondary index record has
already been updated to a different binary value in
a char field, but the collation identifies the old
and new value anyway! */
if (entry && !dtuple_coll_cmp(ientry, entry)) {
mem_heap_free(heap);
if (v_heap) {
mem_heap_free(v_heap);
}
return(TRUE);
}
}
version = prev_version;
}
}
/*****************************************************************//**
Constructs the version of a clustered index record which a consistent
read should see. We assume that the trx id stored in rec is such that
the consistent read should not see rec in its present version.
@return DB_SUCCESS or DB_MISSING_HISTORY */
dberr_t
row_vers_build_for_consistent_read(
/*===============================*/
const rec_t* rec, /*!< in: record in a clustered index; the
caller must have a latch on the page; this
latch locks the top of the stack of versions
of this records */
mtr_t* mtr, /*!< in: mtr holding the latch on rec */
dict_index_t* index, /*!< in: the clustered index */
ulint** offsets,/*!< in/out: offsets returned by
rec_get_offsets(rec, index) */
ReadView* view, /*!< in: the consistent read view */
mem_heap_t** offset_heap,/*!< in/out: memory heap from which
the offsets are allocated */
mem_heap_t* in_heap,/*!< in: memory heap from which the memory for
*old_vers is allocated; memory for possible
intermediate versions is allocated and freed
locally within the function */
rec_t** old_vers,/*!< out, own: old version, or NULL
if the history is missing or the record
does not exist in the view, that is,
it was freshly inserted afterwards */
const dtuple_t**vrow) /*!< out: virtual row */
{
const rec_t* version;
rec_t* prev_version;
trx_id_t trx_id;
mem_heap_t* heap = NULL;
byte* buf;
dberr_t err;
ut_ad(dict_index_is_clust(index));
ut_ad(mtr_memo_contains_page_flagged(mtr, rec, MTR_MEMO_PAGE_X_FIX
| MTR_MEMO_PAGE_S_FIX));
ut_ad(!rw_lock_own(&(purge_sys->latch), RW_LOCK_S));
ut_ad(rec_offs_validate(rec, index, *offsets));
trx_id = row_get_rec_trx_id(rec, index, *offsets);
ut_ad(!view->changes_visible(trx_id, index->table->name));
ut_ad(!vrow || !(*vrow));
version = rec;
for (;;) {
mem_heap_t* prev_heap = heap;
heap = mem_heap_create(1024);
if (vrow) {
*vrow = NULL;
}
/* If purge can't see the record then we can't rely on
the UNDO log record. */
bool purge_sees = trx_undo_prev_version_build(
rec, mtr, version, index, *offsets, heap,
&prev_version, NULL, vrow, 0);
err = (purge_sees) ? DB_SUCCESS : DB_MISSING_HISTORY;
if (prev_heap != NULL) {
mem_heap_free(prev_heap);
}
if (prev_version == NULL) {
/* It was a freshly inserted version */
*old_vers = NULL;
ut_ad(!vrow || !(*vrow));
break;
}
*offsets = rec_get_offsets(
prev_version, index, *offsets, ULINT_UNDEFINED,
offset_heap);
#if defined UNIV_DEBUG || defined UNIV_BLOB_LIGHT_DEBUG
ut_a(!rec_offs_any_null_extern(prev_version, *offsets));
#endif /* UNIV_DEBUG || UNIV_BLOB_LIGHT_DEBUG */
trx_id = row_get_rec_trx_id(prev_version, index, *offsets);
if (view->changes_visible(trx_id, index->table->name)) {
/* The view already sees this version: we can copy
it to in_heap and return */
buf = static_cast<byte*>(
mem_heap_alloc(
in_heap, rec_offs_size(*offsets)));
*old_vers = rec_copy(buf, prev_version, *offsets);
rec_offs_make_valid(*old_vers, index, *offsets);
if (vrow && *vrow) {
*vrow = dtuple_copy(*vrow, in_heap);
dtuple_dup_v_fld(*vrow, in_heap);
}
break;
}
version = prev_version;
}
mem_heap_free(heap);
return(err);
}
/*****************************************************************//**
Constructs the last committed version of a clustered index record,
which should be seen by a semi-consistent read. */
void
row_vers_build_for_semi_consistent_read(
/*====================================*/
const rec_t* rec, /*!< in: record in a clustered index; the
caller must have a latch on the page; this
latch locks the top of the stack of versions
of this records */
mtr_t* mtr, /*!< in: mtr holding the latch on rec */
dict_index_t* index, /*!< in: the clustered index */
ulint** offsets,/*!< in/out: offsets returned by
rec_get_offsets(rec, index) */
mem_heap_t** offset_heap,/*!< in/out: memory heap from which
the offsets are allocated */
mem_heap_t* in_heap,/*!< in: memory heap from which the memory for
*old_vers is allocated; memory for possible
intermediate versions is allocated and freed
locally within the function */
const rec_t** old_vers,/*!< out: rec, old version, or NULL if the
record does not exist in the view, that is,
it was freshly inserted afterwards */
const dtuple_t** vrow) /*!< out: virtual row, old version, or NULL
if it is not updated in the view */
{
const rec_t* version;
mem_heap_t* heap = NULL;
byte* buf;
trx_id_t rec_trx_id = 0;
ut_ad(dict_index_is_clust(index));
ut_ad(mtr_memo_contains_page_flagged(mtr, rec, MTR_MEMO_PAGE_X_FIX
| MTR_MEMO_PAGE_S_FIX));
ut_ad(!rw_lock_own(&(purge_sys->latch), RW_LOCK_S));
ut_ad(rec_offs_validate(rec, index, *offsets));
version = rec;
ut_ad(!vrow || !(*vrow));
for (;;) {
const trx_t* version_trx;
mem_heap_t* heap2;
rec_t* prev_version;
trx_id_t version_trx_id;
version_trx_id = row_get_rec_trx_id(version, index, *offsets);
if (rec == version) {
rec_trx_id = version_trx_id;
}
if (!version_trx_id) {
goto committed_version_trx;
}
trx_sys_mutex_enter();
version_trx = trx_get_rw_trx_by_id(version_trx_id);
/* Because version_trx is a read-write transaction,
its state cannot change from or to NOT_STARTED while
we are holding the trx_sys->mutex. It may change from
ACTIVE to PREPARED or COMMITTED. */
if (version_trx
&& trx_state_eq(version_trx,
TRX_STATE_COMMITTED_IN_MEMORY)) {
version_trx = NULL;
}
trx_sys_mutex_exit();
if (!version_trx) {
committed_version_trx:
/* We found a version that belongs to a
committed transaction: return it. */
#if defined UNIV_DEBUG || defined UNIV_BLOB_LIGHT_DEBUG
ut_a(!rec_offs_any_null_extern(version, *offsets));
#endif /* UNIV_DEBUG || UNIV_BLOB_LIGHT_DEBUG */
if (rec == version) {
*old_vers = rec;
if (vrow) {
*vrow = NULL;
}
break;
}
/* We assume that a rolled-back transaction stays in
TRX_STATE_ACTIVE state until all the changes have been
rolled back and the transaction is removed from
the global list of transactions. */
if (rec_trx_id == version_trx_id) {
/* The transaction was committed while
we searched for earlier versions.
Return the current version as a
semi-consistent read. */
version = rec;
*offsets = rec_get_offsets(version,
index, *offsets,
ULINT_UNDEFINED,
offset_heap);
}
buf = static_cast<byte*>(
mem_heap_alloc(
in_heap, rec_offs_size(*offsets)));
*old_vers = rec_copy(buf, version, *offsets);
rec_offs_make_valid(*old_vers, index, *offsets);
if (vrow && *vrow) {
*vrow = dtuple_copy(*vrow, in_heap);
dtuple_dup_v_fld(*vrow, in_heap);
}
break;
}
DEBUG_SYNC_C("after_row_vers_check_trx_active");
heap2 = heap;
heap = mem_heap_create(1024);
if (!trx_undo_prev_version_build(rec, mtr, version, index,
*offsets, heap,
&prev_version,
in_heap, vrow, 0)) {
mem_heap_free(heap);
heap = heap2;
heap2 = NULL;
goto committed_version_trx;
}
if (heap2) {
mem_heap_free(heap2); /* free version */
}
if (prev_version == NULL) {
/* It was a freshly inserted version */
*old_vers = NULL;
ut_ad(!vrow || !(*vrow));
break;
}
version = prev_version;
*offsets = rec_get_offsets(version, index, *offsets,
ULINT_UNDEFINED, offset_heap);
#if defined UNIV_DEBUG || defined UNIV_BLOB_LIGHT_DEBUG
ut_a(!rec_offs_any_null_extern(version, *offsets));
#endif /* UNIV_DEBUG || UNIV_BLOB_LIGHT_DEBUG */
}/* for (;;) */
if (heap) {
mem_heap_free(heap);
}
}
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