Versioned sc structs

Signed-off-by: Mark Hannum <[email protected]>

bdb/llmeta.c

@@ -36,6 +36,8 @@
 #include <sys/poll.h>
 #include "debug_switches.h"
 #include "alias.h"
+#include "sc_version.h"
+
 extern int gbl_maxretries;
 extern int gbl_disable_access_controls;
 extern int get_csc2_version_tran(const char *table, tran_type *tran);
@@ -118,7 +120,7 @@ typedef enum {
                                   data = no data
                                   does db use authentication? */
     ,
-    LLMETA_ACCESSCONTROL_TABLExNODE = 19  /* XXX Deprecated */
+    LLMETA_ACCESSCONTROL_TABLExNODE = 19 /* XXX Deprecated */
 
     ,
     LLMETA_SQLITE_STAT1_PREV_DONT_USE = 20 /* store previous sqlite-stat1 records- dont use this. */
@@ -176,7 +178,8 @@ typedef enum {
     LLMETA_LUA_SFUNC_FLAG = 54,
     LLMETA_NEWSC_REDO_GENID = 55, /* 55 + TABLENAME + GENID -> MAX-LSN */
     LLMETA_SCHEMACHANGE_STATUS_V2 = 56,
-    LLMETA_SCHEMACHANGE_LIST = 57, /* list of all sc-s in a uuid txh */
+    LLMETA_SCHEMACHANGE_STATUS_VERSIONED = 57,
+    LLMETA_SCHEMACHANGE_LIST = 58, /* list of all sc-s in a uuid txh */
 } llmetakey_t;
 
 struct llmeta_file_type_key {
@@ -11336,30 +11339,43 @@ int bdb_del_view(tran_type *t, const char *view_name)
   coincide with the first 4 bytes of the rqid (fastseed) stored as the first
   member in old (7.0's) LLMETA_SCHEMACHANGE_STATUS payload.
 */
-static int buf_get_schemachange_key_type(void *p_buf, void *p_buf_end)
+static int buf_get_schemachange_key_type(void *p_buf, void *p_buf_end, int *version)
 {
     int first = 0;
 
-    if (p_buf >= p_buf_end) return -1;
+    if (p_buf >= p_buf_end)
+        return -1;
 
-    buf_get(&first, sizeof(first), p_buf, p_buf_end);
+    p_buf = (void *)buf_get(&first, sizeof(first), p_buf, p_buf_end);
 
+    if (first == SC_VERSIONED) {
+        buf_get(version, sizeof(int), p_buf, p_buf_end);
+        return LLMETA_SCHEMACHANGE_STATUS_VERSIONED;
+    }
     if (first > SC_INVALID && first < SC_LAST) {
         return LLMETA_SCHEMACHANGE_STATUS_V2;
     }
     return LLMETA_SCHEMACHANGE_STATUS;
 }
 
-void *buf_get_schemachange(struct schema_change_type *s, void *p_buf,
-                           void *p_buf_end)
+void *buf_get_schemachange(struct schema_change_type *s, void *p_buf, void *p_buf_end)
 {
-    int sc_key_type = buf_get_schemachange_key_type(p_buf, p_buf_end);
+    int version = 0;
+    int sc_key_type = buf_get_schemachange_key_type(p_buf, p_buf_end, &version);
 
     switch (sc_key_type) {
+    case LLMETA_SCHEMACHANGE_STATUS_VERSIONED:
+        /* Increment & delete code to deprecate old versions */
+        if (version < 2 || version > SC_VERSION) {
+            logmsg(LOGMSG_ERROR, "%s: unknown sc-version %d\n", __func__, version);
+            return NULL;
+        }
+        p_buf = p_buf + sizeof(int) + sizeof(int);
+        return buf_get_schemachange_versioned(s, (void *)p_buf, (void *)p_buf_end, version);
     case LLMETA_SCHEMACHANGE_STATUS:
         return buf_get_schemachange_v1(s, (void *)p_buf, (void *)p_buf_end);
     case LLMETA_SCHEMACHANGE_STATUS_V2:
-        return buf_get_schemachange_v2(s, (void *)p_buf, (void *)p_buf_end);
+        return buf_get_schemachange_versioned(s, (void *)p_buf, (void *)p_buf_end, 2);
     default:
         break;
     }

db/config.c

@@ -447,6 +447,8 @@ static char *legacy_options[] = {
     "setattr max_sql_idle_time 864000",
     "retrieve_gen_from_ckp 0",
     "recovery_ckp 0",
+    "sc_versioned 0",
+    "sc_current_version 2",
 };
 // clang-format on
 

db/db_tunables.c

@@ -304,6 +304,8 @@ extern int gbl_memp_dump_cache_threshold;
 extern int gbl_disable_ckp;
 extern int gbl_abort_on_illegal_log_put;
 extern int gbl_sc_close_txn;
+extern int gbl_sc_versioned;
+extern int gbl_sc_current_version;
 extern int gbl_master_sends_query_effects;
 extern int gbl_create_dba_user;
 extern int gbl_lock_dba_user;

db/db_tunables.h

@@ -2385,6 +2385,10 @@ REGISTER_TUNABLE("wal_osync", "Open WAL files using the O_SYNC flag (Default: of
                  NULL, NULL, NULL, NULL);
 REGISTER_TUNABLE("sc_headroom", "Percentage threshold for low headroom calculation. (Default: 10)", TUNABLE_DOUBLE,
                  &gbl_sc_headroom, INTERNAL | SIGNED, NULL, NULL, NULL, NULL);
+REGISTER_TUNABLE("sc_versioned", "Enable versioned schema changes (Default: on)", TUNABLE_BOOLEAN, &gbl_sc_versioned, 0,
+                 NULL, NULL, NULL, NULL);
+REGISTER_TUNABLE("sc_current_version", "Current schema-change version (Default: 2)", TUNABLE_INTEGER,
+                 &gbl_sc_current_version, 0, NULL, NULL, NULL, NULL);
 REGISTER_TUNABLE("fdb_incoherence_percentage", "Generate random incoherent errors in remsql", TUNABLE_INTEGER,
                  &gbl_fdb_incoherence_percentage, INTERNAL, NULL, percent_verify, NULL, NULL);
 REGISTER_TUNABLE("fdb_socket_timeout_ms", "Timeout ms for fdb communications.  (Default: 10000)", TUNABLE_INTEGER,

schemachange/sc_struct.c

@@ -16,6 +16,7 @@
 
 #include "schemachange.h"
 #include "sc_struct.h"
+#include "sc_version.h"
 #include "logmsg.h"
 #include "sc_csc2.h"
 #include "sc_schema.h"
@@ -132,6 +133,10 @@ static size_t _partition_packed_size(struct comdb2_partition *p)
     }
 }
 
+/* To change, increment SC_VERSION & set legacy-defaults to old version */
+int gbl_sc_current_version = SC_VERSION;
+int gbl_sc_versioned = 1;
+
 size_t schemachange_packed_size(struct schema_change_type *s)
 {
     s->tablename_len = strlen(s->tablename) + 1;
@@ -161,6 +166,20 @@ size_t schemachange_packed_size(struct schema_change_type *s)
         sizeof(s->usedbtablevers) + sizeof(s->qdb_file_ver) +
         _partition_packed_size(&s->partition);
 
+    if (gbl_sc_versioned) {
+        s->packed_len += 8;
+        /*
+        int sc_current_version = gbl_sc_current_version;
+
+        if (sc_current_version > 2) {
+            s->packed_len += XXXX;
+        }
+        if (sc_current_version > 3) {
+            s->packed_len += XXXX;
+        }
+        */
+    }
+
     return s->packed_len;
 }
 
@@ -186,8 +205,20 @@ static void *buf_put_dests(struct schema_change_type *s, void *p_buf,
 
 void *buf_put_schemachange(struct schema_change_type *s, void *p_buf, void *p_buf_end)
 {
+    int version = gbl_sc_current_version;
+    if (p_buf >= p_buf_end)
+        return NULL;
 
-    if (p_buf >= p_buf_end) return NULL;
+    if (gbl_sc_versioned) {
+        int neg1 = -1, vers = version;
+        p_buf = buf_put(&neg1, sizeof(neg1), p_buf, p_buf_end);
+        p_buf = buf_put(&vers, sizeof(vers), p_buf, p_buf_end);
+    }
+    /*
+     * if (version > 2) {
+     *   p_buf = buf_put(&s->new_field, sizeof(s->new_field), p_buf, p_buf_end);
+     * }
+     */
 
     p_buf = buf_put(&s->kind, sizeof(s->kind), p_buf, p_buf_end);
 
@@ -557,11 +588,18 @@ void *buf_get_schemachange_v1(struct schema_change_type *s, void *p_buf,
     return p_buf;
 }
 
-void *buf_get_schemachange_v2(struct schema_change_type *s,
-                              void *p_buf, void *p_buf_end)
+void *buf_get_schemachange_versioned(struct schema_change_type *s, void *p_buf, void *p_buf_end, int version)
 {
 
-    if (p_buf >= p_buf_end) return NULL;
+    if (p_buf >= p_buf_end)
+        return NULL;
+    /*
+     * if (version > 2) {
+     *    buf_get(&s->new_field, sizeof(s->new_field), p_buf, p_buf_end);
+     * } else {
+     *    s->new_field = -1;
+     * }
+     */
 
     p_buf = (uint8_t *)buf_get(&s->kind, sizeof(s->kind), p_buf, p_buf_end);
 

schemachange/sc_version.h

@@ -0,0 +1,22 @@
+/*
+   Copyright 2025 Bloomberg Finance L.P.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+ */
+
+#ifndef INCLUDE_SC_VERSION_H
+#define INCLUDE_SC_VERSION_H
+
+#define SC_VERSION 2
+
+#endif

schemachange/schemachange.h

@@ -90,6 +90,7 @@ struct timepart_view;
 
 /* in sync with do_schema_change_if */
 enum schema_change_kind {
+    SC_VERSIONED = -1,
     SC_INVALID = 0,
     SC_LEGACY_QUEUE = 1,
     SC_LEGACY_MORESTRIPE = 2,
@@ -429,8 +430,7 @@ void *buf_get_schemachange(struct schema_change_type *s, void *p_buf,
                            void *p_buf_end);
 void *buf_get_schemachange_v1(struct schema_change_type *s, void *p_buf,
                               void *p_buf_end);
-void *buf_get_schemachange_v2(struct schema_change_type *s, void *p_buf,
-                              void *p_buf_end);
+void *buf_get_schemachange_versioned(struct schema_change_type *s, void *p_buf, void *p_buf_end, int version);
 /* This belong into sc_util.h */
 int check_sc_ok(struct schema_change_type *s);
 

tests/tunables.test/t00_all_tunables.expected

@@ -860,6 +860,7 @@
 (name='sc_async', description='Run transactional schema changes asynchronously.', type='BOOLEAN', value='ON', read_only='N')
 (name='sc_async_maxthreads', description='Max number of threads for asynchronous schema changes.', type='INTEGER', value='5', read_only='N')
 (name='sc_check_lockwaits_sec', description='Frequency of checking lockwaits during schemachange (in seconds).', type='INTEGER', value='1', read_only='N')
+(name='sc_current_version', description='Current schema-change version (Default: 2)', type='INTEGER', value='2', read_only='N')
 (name='sc_decrease_thrds_on_deadlock', description='Decrease number of schema change threads on deadlock - way to have schema change backoff.', type='BOOLEAN', value='ON', read_only='N')
 (name='sc_del_unused_files_threshold', description='', type='INTEGER', value='30000', read_only='Y')
 (name='sc_delay_verify_error', description='', type='INTEGER', value='100', read_only='N')
@@ -876,6 +877,7 @@
 (name='sc_resume_watchdog_timer', description='sc_resuming_watchdog timer', type='INTEGER', value='60', read_only='N')
 (name='sc_status_max_rows', description='Max number of rows returned in comdb2_sc_status (Default: 1000)', type='INTEGER', value='1000', read_only='N')
 (name='sc_use_num_threads', description='Start up to this many threads for parallel rebuilding during schema change. 0 means use one per dtastripe. Setting is capped at dtastripe.', type='INTEGER', value='0', read_only='N')
+(name='sc_versioned', description='Enable versioned schema changes (Default: on)', type='BOOLEAN', value='ON', read_only='N')
 (name='sc_via_ddl_only', description='If set, we don't do checks needed for comdb2sc.', type='BOOLEAN', value='OFF', read_only='N')
 (name='scatterkeys', description='', type='BOOLEAN', value='OFF', read_only='N')
 (name='scconvert_finish_delay', description='Delay returning from convert_record when a stripe finishes. This would create a scenario where scgenids are on the right of any new genids to reproduce a vutf8 schema change bug. ', type='BOOLEAN', value='OFF', read_only='N')