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MDEV-36297: Ability to backup selected partitions only #3891

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fa081aa
Ability to backup selected partitions only
slawomir-pryczek Mar 13, 2025
c648301
Debug variable fix
slawomir-pryczek Mar 13, 2025
fea8b5f
Update mysqldump.cc
slawomir-pryczek Mar 28, 2025
ed1636e
Cleaning up comments
slawomir-pryczek Mar 28, 2025
f1de335
Fix for no partitions mode
slawomir-pryczek Mar 28, 2025
728f34f
Warning fix
slawomir-pryczek Mar 28, 2025
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174 changes: 166 additions & 8 deletions client/mysqldump.cc
100644 → 100755
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Original file line number Diff line number Diff line change
Expand Up @@ -126,7 +126,7 @@ static my_bool verbose= 0, opt_no_create_info= 0, opt_no_data= 0, opt_no_data_m
opt_single_transaction=0, opt_comments= 0, opt_compact= 0,
opt_hex_blob=0, opt_order_by_primary=0, opt_order_by_size = 0,
opt_ignore=0, opt_complete_insert= 0, opt_drop_database= 0,
opt_replace_into= 0,
opt_replace_into= 0, opt_partitions = 0,
opt_dump_triggers= 0, opt_routines=0, opt_tz_utc=1,
opt_slave_apply= 0,
opt_include_master_host_port= 0,
Expand Down Expand Up @@ -270,6 +270,13 @@ static struct my_option my_long_options[] =
{"no-tablespaces", 'y',
"Do not dump any tablespace information.",
&opt_notspcs, &opt_notspcs, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
{"partitions", 0,
"Allows the user to specify partition in table names, please use "
"table_name#partition_name format. Double hash to escape # character. "
"Please add multiple entries for a single table to select multiple partitions. "
"These will be merged and produce a single table with selected "
"partitions in the output.",
&opt_partitions, &opt_partitions, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0 ,0, 0},
{"add-drop-database", 0, "Add a DROP DATABASE before each create.",
&opt_drop_database, &opt_drop_database, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0,
0},
Expand Down Expand Up @@ -1350,6 +1357,11 @@ static int get_options(int *argc, char ***argv)
my_progname_short);
return(EX_USAGE);
}
if (opt_databases && opt_partitions)
{
fprintf(stderr, "%s: --databases and --partitions can't be used together.\n", my_progname_short);
return(EX_USAGE);
}
if (ignore_database.records && !opt_alldbs && !(opt_wildcards && opt_databases))
{
fprintf(stderr,
Expand Down Expand Up @@ -4209,7 +4221,7 @@ static void send_query_completion_func(MYSQL* mysql, const char* query,
*/


static void dump_table(const char *table, const char *db, const uchar *hash_key, size_t len)
static void dump_table(const char *table, const char *db, const uchar *hash_key, size_t len, const char * partition = NULL)
{
char ignore_flag;
char buf[200], table_buff[NAME_LEN+3];
Expand Down Expand Up @@ -4360,6 +4372,11 @@ static void dump_table(const char *table, const char *db, const uchar *hash_key,
dynstr_append_checked(&query_string, qdatabase);
dynstr_append_checked(&query_string, ".");
dynstr_append_checked(&query_string, result_table);
if (partition != NULL) {
dynstr_append_checked(&query_string, " PARTITION (");
dynstr_append_checked(&query_string, partition);
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@vuvova vuvova Dec 5, 2025

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quote_name(partition) here instead of duplicating backticks in get_partition_from_table_name()

dynstr_append_checked(&query_string, ") ");
}

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@vuvova vuvova Dec 5, 2025

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I think here, inside if (multi_file_output), when --partitions is specified, it should create one file per partition, not one file per table.

if (versioned)
vers_append_system_time(&query_string);
Expand Down Expand Up @@ -4400,14 +4417,29 @@ static void dump_table(const char *table, const char *db, const uchar *hash_key,
}
else
{
print_comment(md_result_file, 0,
"\n--\n-- Dumping data for table %s\n--\n",
fix_for_comment(result_table));
if (partition == NULL)
{
print_comment(md_result_file, 0,
"\n--\n-- Dumping data for table %s\n--\n",
fix_for_comment(result_table));
}
else
{
print_comment(md_result_file, 0,
"\n--\n-- Dumping data for table %s, partition %s\n--\n",
fix_for_comment(result_table), partition);
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@vuvova vuvova Dec 5, 2025

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fix_for_comment(partition)

}

dynstr_append_checked(&query_string, "SELECT /*!40001 SQL_NO_CACHE */ ");
dynstr_append_checked(&query_string, select_field_names.str);
dynstr_append_checked(&query_string, " FROM ");
dynstr_append_checked(&query_string, result_table);
if (partition != NULL) {
dynstr_append_checked(&query_string, " PARTITION (");
dynstr_append_checked(&query_string, partition);
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@vuvova vuvova Dec 5, 2025

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quote_name()

dynstr_append_checked(&query_string, ") ");
}

if (versioned)
vers_append_system_time(&query_string);

Expand Down Expand Up @@ -6146,7 +6178,50 @@ static int get_sys_var_lower_case_table_names()
return lower_case_table_names;
}

// Returns partition name from table name. NULL if no partition is specified.
// Will put \0 in place of partition separator, so after return
// *tablename will contain only table name.
//
// Will treat double separator as escape in table name
// Will replace backtick in partition name with double backtick
// You need to do my_free on the result, if not NULL
static char* get_partition_from_table_name(char *tablename, const char separator = '#')
{
size_t namelen = strlen(tablename);
int jj = 0;
for (size_t ii=0; ii<namelen; ii++)
{
if (tablename[ii] != separator)
{
tablename[jj++] = tablename[ii];
continue;
}

if (ii+1 < namelen && tablename[ii+1] == separator)
{
// we found escaped (table##name) hash, put # in table name and move forward
ii++;
tablename[jj++] = separator;
}
else
{
// we found partition name separator, next char is the partition name
tablename[jj++] = 0x0;
ii=ii+1;

jj=0;
char *tmp = (char*) my_malloc(PSI_NOT_INSTRUMENTED, (strlen(&tablename[ii])*2+1) * sizeof(char), MYF(MY_WME | MY_ZEROFILL));
for (; tablename[ii] != 0; ii++) {
tmp[jj++] = tablename[ii];
if (tablename[ii] == '`')
tmp[jj++] = '`';
}
return tmp;
}
}

return NULL;
}

static int dump_selected_tables(char *db, char **table_names, int tables)
{
Expand All @@ -6156,6 +6231,69 @@ static int dump_selected_tables(char *db, char **table_names, int tables)
int lower_case_table_names;
DBUG_ENTER("dump_selected_tables");

// remove partition names from table names, if we have separator defined
// put all partition names into **partition names variable, NULL = none
DYNAMIC_STRING **partition_names = NULL;
if (opt_partitions && tables > 0)
{
char ** new_table_names = (char **)my_malloc(PSI_NOT_INSTRUMENTED, 5 * sizeof (char *), MYF(MY_WME));
partition_names = (DYNAMIC_STRING **) my_malloc(PSI_NOT_INSTRUMENTED, tables * sizeof (DYNAMIC_STRING **), MYF(MY_WME));

for (int i=0; i<tables; i++)
{
new_table_names[i] = NULL;
partition_names[i] = NULL;
}

for (int i=0; i<tables; i++)
{
char *tname = table_names[i];
char *pname = get_partition_from_table_name(table_names[i]);
int tpos = 0;

// maybe we have this table added already
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@vuvova vuvova Dec 5, 2025

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I'm not sure it's a good idea. first you force the user to specify the table name many times, then you manually remove duplicates. I like your earlier idea of table#part1,part2,.. more.

Except that it should rather be table#part1#part2#... — there's no need to introduce two different separators.

Actually, table,part1,part2,... looks nicer. Perhaps --partitions should take the separator as a argument?

for (int j=0; j<tables; j++)
{
tpos = j;
if (new_table_names[j] == NULL || cmp_table(new_table_names[j], tname) == 0)
break;
}
new_table_names[tpos] = tname;

if (pname == NULL)
continue;
if (strlen(pname) == 0)
{
maybe_die(EX_USAGE, "Partition name can't be empty, please specify partition name for table %s", tname);
continue;
}

DYNAMIC_STRING *ppart = partition_names[tpos];
if (ppart == NULL) {
ppart = (DYNAMIC_STRING*) my_malloc(PSI_NOT_INSTRUMENTED, sizeof(DYNAMIC_STRING), MYF(MY_WME | MY_ZEROFILL));
init_dynamic_string_checked(ppart, "", 256, 1024);
partition_names[tpos] = ppart;
}
else
dynstr_append_checked(ppart, ", ");
dynstr_append_checked(ppart, "`");
dynstr_append_checked(ppart, pname);
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@vuvova vuvova Dec 5, 2025

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quote_name() I suppose

dynstr_append_checked(ppart, "`");
}

for (int i=0; i<tables; i++)
table_names[i] = new_table_names[i];
for (int i=0; i<tables; i++)
{
if (table_names[i] == NULL)
{
tables = i;
break;
}
}
my_free(new_table_names);
}

if (init_dumping(db, init_dumping_tables))
DBUG_RETURN(1);

Expand All @@ -6171,7 +6309,9 @@ static int dump_selected_tables(char *db, char **table_names, int tables)
lower_case_table_names = get_sys_var_lower_case_table_names();

init_dynamic_string_checked(&lock_tables_query, "LOCK TABLES ", 256, 1024);
for (; tables > 0 ; tables-- , table_names++)

DYNAMIC_STRING ** partition_names_pos = partition_names;
for (int table_num=0; table_num<tables; table_num++, table_names++)
{
/* the table name passed on commandline may be wrong case */
if ((*pos= get_actual_table_name(*table_names, lower_case_table_names,
Expand All @@ -6184,6 +6324,12 @@ static int dump_selected_tables(char *db, char **table_names, int tables)
dynstr_append_checked(&lock_tables_query, " READ /*!32311 LOCAL */,");
}
pos++;

// move partition name, if we're skipping a table
if (partition_names != NULL) {
*partition_names_pos= partition_names[table_num];
partition_names_pos++;
}
}
else
{
Expand All @@ -6197,6 +6343,7 @@ static int dump_selected_tables(char *db, char **table_names, int tables)
}
}
end= pos;
partition_names_pos= partition_names;

/* Can't LOCK TABLES in I_S / P_S, so don't try. */
if (lock_tables && !is_IS_or_PS(db))
Expand Down Expand Up @@ -6260,10 +6407,21 @@ static int dump_selected_tables(char *db, char **table_names, int tables)
/* Dump each selected table */
for (pos= dump_tables; pos < end; pos++)
{
char *partition = NULL;
if (partition_names_pos != NULL && *partition_names_pos != NULL) {
partition = (*partition_names_pos)->str;
partition_names_pos++;
}

if (check_if_ignore_table(*pos, table_type) & IGNORE_SEQUENCE_TABLE)
continue;
DBUG_PRINT("info",("Dumping table %s", *pos));
dump_table(*pos, db, NULL, 0);

if (partition == NULL)
DBUG_PRINT("info",("Dumping table %s", *pos));
else
DBUG_PRINT("info",("Dumping table %s, partition %s", *pos, partition));

dump_table(*pos, db, NULL, 0, partition);
if (opt_dump_triggers &&
mysql_get_server_version(mysql) >= 50009)
{
Expand Down