From 477577ade5673eac1ac3215631c8a0a9abac7859 Mon Sep 17 00:00:00 2001 From: Xiaoguang Sun Date: Thu, 6 Jul 2023 18:15:46 +0800 Subject: [PATCH] Update TiDB Serverless limitations (#13970) --- TOC-tidb-cloud.md | 1 + tidb-cloud/limited-sql-features.md | 249 +++++++++++++++++++++++++++ tidb-cloud/serverless-limitations.md | 47 ++--- 3 files changed, 275 insertions(+), 22 deletions(-) create mode 100644 tidb-cloud/limited-sql-features.md diff --git a/TOC-tidb-cloud.md b/TOC-tidb-cloud.md index 298679d343b0f..a752dd3aa1247 100644 --- a/TOC-tidb-cloud.md +++ b/TOC-tidb-cloud.md @@ -273,6 +273,7 @@ - [Scheduling](/tidb-scheduling.md) - [TiDB Dedicated Limitations and Quotas](/tidb-cloud/limitations-and-quotas.md) - [TiDB Serverless Limitations](/tidb-cloud/serverless-limitations.md) + - [Limited SQL Features on TiDB Cloud](/tidb-cloud/limited-sql-features.md) - [TiDB Limitations](/tidb-limitations.md) - Benchmarks - [TPC-C Performance Test Report](/tidb-cloud/v7.1.0-performance-benchmarking-with-tpcc.md) diff --git a/tidb-cloud/limited-sql-features.md b/tidb-cloud/limited-sql-features.md new file mode 100644 index 0000000000000..ba4a34600a88f --- /dev/null +++ b/tidb-cloud/limited-sql-features.md @@ -0,0 +1,249 @@ +--- +title: Limited SQL Features on TiDB Cloud +summary: Learn about the limited SQL features on TiDB Cloud. +--- + +# Limited SQL features on TiDB Cloud + +TiDB Cloud works with almost all workloads that TiDB supports, but there are some feature differences between TiDB Self-Hosted and TiDB Dedicated/Serverless. This document describes the limitations of SQL features on TiDB Cloud. We are constantly filling in the feature gaps between TiDB Self-Hosted and TiDB Dedicated/Serverless. If you require these features or capabilities in the gap, [contact us](/tidb-cloud/tidb-cloud-support.md) for a feature request. + +## Statements + +### Placement and range management + +| Statement | TiDB Dedicated | TiDB Serverless | +|:-|:-|:-| +| `ALTER PLACEMENT POLICY` | Supported | Not supported [^1] | +| `CREATE PLACEMENT POLICY` | Supported | Not supported [^1] | +| `DROP PLACEMENT POLICY` | Supported | Not supported [^1] | +| `SHOW CREATE PLACEMENT POLICY` | Supported | Not supported [^1] | +| `SHOW PLACEMENT` | Supported | Not supported [^1] | +| `SHOW PLACEMENT FOR` | Supported | Not supported [^1] | +| `SHOW PLACEMENT LABELS` | Supported | Not supported [^1] | +| `SHOW TABLE REGIONS` | Supported | Not supported [^1] | +| `SPLIT REGION` | Supported | Not supported [^1] | + +### Resource groups + +| Statement | TiDB Dedicated | TiDB Serverless | +|:-|:-|:-| +| `ALTER RESOURCE GROUP` | Supported | Not supported [^2] | +| `CALIBRATE RESOURCE` | Supported | Not supported [^2] | +| `CREATE RESOURCE GROUP` | Supported | Not supported [^2] | +| `DROP RESOURCE GROUP` | Supported | Not supported [^2] | +| `SET RESOURCE GROUP` | Supported | Not supported [^2] | +| `SHOW CREATE RESOURCE GROUP` | Supported | Not supported [^2] | + +### Others + +| Statement | TiDB Dedicated | TiDB Serverless | +|:-|:-|:-| +| `BACKUP` | Supported | Not supported [^3] | +| `SHOW BACKUPS` | Supported | Not supported [^3] | +| `RESTORE` | Supported | Not supported [^3] | +| `SHOW RESTORES` | Supported | Not supported [^3] | +| `ADMIN RESET TELEMETRY_ID` | Supported | Telemetry is not supported on TiDB Serverless. | +| `ADMIN SHOW TELEMETRY` | Not supported [^4] | Not supported [^4] | +| `ADMIN SHOW SLOW` | Supported | Not supported [^5] | +| `ADMIN PLUGINS ENABLE` | Supported | Not supported [^8] | +| `ADMIN PLUGINS DISABLE` | Supported | Not supported [^8] | +| `ALTER INSTANCE RELOAD TLS` | Supported | TiDB Serverless automatically refreshes the TLS certificate. | +| `LOAD DATA INFILE` | Only supports `LOAD DATA LOCAL INFILE` | Only supports `LOAD DATA LOCAL INFILE` | +| `CHANGE DRAINER` | Not supported [^7] | Not supported [^7] | +| `CHANGE PUMP` | Not supported [^7] | Not supported [^7] | +| `FLASHBACK CLUSTER TO TIMESTAMP` | Supported | Not supported [^3] | +| `LOAD STATS` | Supported | Not supported | +| `SET CONFIG` | Not supported [^4] | Not supported [^4] | +| `SHOW CONFIG` | Not supported [^4] | Not supported [^4] | +| `SHOW DRAINER STATUS` | Not supported [^7] | Not supported [^7] | +| `SHOW PLUGINS` | Supported | Not supported [^8] | +| `SHOW PUMP STATUS` | Not supported [^7] | Not supported [^7] | +| `SHUTDOWN` | Not supported [^4] | Not supported [^4] | + +## Functions and operators + +| Function and operator | TiDB Dedicated | TiDB Serverless | +|:-|:-|:-| +| `SLEEP` | No Limitation | The [`SLEEP()` function](https://docs.pingcap.com/tidbcloud/miscellaneous-functions) has a limitation wherein it can only support a maximum sleep time of 300 seconds.| + +## System tables + +| Database | Table | TiDB Dedicated | TiDB Serverless | +|:-|:-|:-|:-| +| `information_schema` | `ATTRIBUTES` | Supported | Not supported [^1] | +| `information_schema` | `CLUSTER_CONFIG` | Not supported [^4] | Not supported [^4] | +| `information_schema` | `CLUSTER_HARDWARE` | Not supported [^4] | Not supported [^4] | +| `information_schema` | `CLUSTER_INFO` | Supported | Not supported [^1] | +| `information_schema` | `CLUSTER_LOAD` | Not supported [^4] | Not supported [^4] | +| `information_schema` | `CLUSTER_LOG` | Not supported [^4] | Not supported [^4] | +| `information_schema` | `CLUSTER_SLOW_QUERY` | Supported | Not supported [^5] | +| `information_schema` | `CLUSTER_STATEMENTS_SUMMARY` | Supported | Not supported [^6] | +| `information_schema` | `CLUSTER_STATEMENTS_SUMMARY_EVICTED` | Supported | Not supported [^6] | +| `information_schema` | `CLUSTER_STATEMENTS_SUMMARY_HISTORY` | Supported | Not supported [^6] | +| `information_schema` | `CLUSTER_SYSTEMINFO` | Not supported [^4] | Not supported [^4] | +| `information_schema` | `INSPECTION_RESULT` | Not supported [^4] | Not supported [^4] | +| `information_schema` | `INSPECTION_RULES` | Not supported [^4] | Not supported [^4] | +| `information_schema` | `INSPECTION_SUMMARY` | Not supported [^4] | Not supported [^4] | +| `information_schema` | `METRICS_SUMMARY` | Not supported [^4] | Not supported [^4] | +| `information_schema` | `METRICS_SUMMARY_BY_LABEL` | Not supported [^4] | Not supported [^4] | +| `information_schema` | `METRICS_TABLES` | Not supported [^4] | Not supported [^4] | +| `information_schema` | `PLACEMENT_POLICIES` | Supported | Not supported [^1] | +| `information_schema` | `RESOURCE_GROUPS` | Supported | Not supported [^2] | +| `information_schema` | `SLOW_QUERY` | Supported | Not supported [^5] | +| `information_schema` | `STATEMENTS_SUMMARY` | Supported | Not supported [^6] | +| `information_schema` | `STATEMENTS_SUMMARY_EVICTED` | Supported | Not supported [^6] | +| `information_schema` | `STATEMENTS_SUMMARY_HISTORY` | Supported | Not supported [^6] | +| `information_schema` | `TIDB_HOT_REGIONS` | Not supported [^4] | Not supported [^4] | +| `information_schema` | `TIDB_HOT_REGIONS_HISTORY` | Supported | Not supported [^1] | +| `information_schema` | `TIDB_SERVERS_INFO` | Supported | Not supported [^1] | +| `information_schema` | `TIFLASH_SEGMENTS` | Supported | Not supported [^1] | +| `information_schema` | `TIFLASH_TABLES` | Supported | Not supported [^1] | +| `information_schema` | `TIKV_REGION_PEERS` | Supported | Not supported [^1] | +| `information_schema` | `TIKV_REGION_STATUS` | Supported | Not supported [^1] | +| `information_schema` | `TIKV_STORE_STATUS` | Supported | Not supported [^1] | +| `performance_schema` | `pd_profile_allocs` | Not supported [^4] | Not supported [^4] | +| `performance_schema` | `pd_profile_block` | Not supported [^4] | Not supported [^4] | +| `performance_schema` | `pd_profile_cpu` | Not supported [^4] | Not supported [^4] | +| `performance_schema` | `pd_profile_goroutines` | Not supported [^4] | Not supported [^4] | +| `performance_schema` | `pd_profile_memory` | Not supported [^4] | Not supported [^4] | +| `performance_schema` | `pd_profile_mutex` | Not supported [^4] | Not supported [^4] | +| `performance_schema` | `tidb_profile_allocs` | Not supported [^4] | Not supported [^4] | +| `performance_schema` | `tidb_profile_block` | Not supported [^4] | Not supported [^4] | +| `performance_schema` | `tidb_profile_cpu` | Not supported [^4] | Not supported [^4] | +| `performance_schema` | `tidb_profile_goroutines` | Not supported [^4] | Not supported [^4] | +| `performance_schema` | `tidb_profile_memory` | Not supported [^4] | Not supported [^4] | +| `performance_schema` | `tidb_profile_mutex` | Not supported [^4] | Not supported [^4] | +| `performance_schema` | `tikv_profile_cpu` | Not supported [^4] | Not supported [^4] | +| `mysql` | `expr_pushdown_blacklist` | Not supported [^4] | Not supported [^4] | +| `mysql` | `gc_delete_range` | Not supported [^4] | Not supported [^4] | +| `mysql` | `gc_delete_range_done` | Not supported [^4] | Not supported [^4] | +| `mysql` | `opt_rule_blacklist` | Not supported [^4] | Not supported [^4] | +| `mysql` | `tidb` | Not supported [^4] | Not supported [^4] | +| `mysql` | `tidb_ttl_job_history` | Supported | Not supported [^9] | +| `mysql` | `tidb_ttl_table_status` | Supported | Not supported [^9] | +| `mysql` | `tidb_ttl_task` | Supported | Not supported [^9] | + +## System variables + +| Variable | TiDB Dedicated | TiDB Serverless | +|:-|:-|:-| +| `datadir` | No limitation | Not supported [^1] | +| `interactive_timeout` | No limitation | Read-only [^11] | +| `max_allowed_packet` | No limitation | Read-only [^11] | +| `plugin_dir` | No limitation | Not supported [^8] | +| `plugin_load` | No limitation | Not supported [^8] | +| `skip_name_resolve` | No limitation | Read-only [^11] | +| `sql_log_bin` | No limitation | Read-only [^11] | +| `tidb_cdc_write_source` | No limitation | Read-only [^11] | +| `tidb_check_mb4_value_in_utf8` | Not supported [^4] | Not supported [^4] | +| `tidb_config` | Not supported [^4] | Not supported [^4] | +| `tidb_ddl_disk_quota` | No limitation | Read-only [^11] | +| `tidb_ddl_enable_fast_reorg` | No limitation | Read-only [^11] | +| `tidb_ddl_error_count_limit` | No limitation | Read-only [^11] | +| `tidb_ddl_flashback_concurrency` | No limitation | Read-only [^11] | +| `tidb_ddl_reorg_batch_size` | No limitation | Read-only [^11] | +| `tidb_ddl_reorg_priority` | No limitation | Read-only [^11] | +| `tidb_ddl_reorg_worker_cnt` | No limitation | Read-only [^11] | +| `tidb_enable_1pc` | No limitation | Read-only [^11] | +| `tidb_enable_async_commit` | No limitation | Read-only [^11] | +| `tidb_enable_auto_analyze` | No limitation | Read-only [^11] | +| `tidb_enable_collect_execution_info` | Not supported [^4] | Not supported [^4] | +| `tidb_enable_ddl` | No limitation | Read-only [^11] | +| `tidb_enable_gc_aware_memory_track` | No limitation | Read-only [^11] | +| `tidb_enable_gogc_tuner` | No limitation | Read-only [^11] | +| `tidb_enable_local_txn` | No limitation | Read-only [^11] | +| `tidb_enable_resource_control` | No limitation | Read-only [^11] | +| `tidb_enable_slow_log` | Not supported [^4] | Not supported [^4] | +| `tidb_enable_stmt_summary` | No limitation | Read-only [^11] | +| `tidb_enable_telemetry` | Not supported [^4] | Not supported [^4] | +| `tidb_enable_top_sql` | No limitation | Read-only [^11] | +| `tidb_enable_tso_follower_proxy` | No limitation | Read-only [^11] | +| `tidb_expensive_query_time_threshold` | Not supported [^4] | Not supported [^4] | +| `tidb_force_priority` | Not supported [^4] | Not supported [^4] | +| `tidb_gc_concurrency` | No limitation | Read-only [^11] | +| `tidb_gc_enable` | No limitation | Read-only [^11] | +| `tidb_gc_life_time` | No limitation | Read-only [^11] | +| `tidb_gc_max_wait_time` | No limitation | Read-only [^11] | +| `tidb_gc_run_interval` | No limitation | Read-only [^11] | +| `tidb_gc_scan_lock_mode` | No limitation | Read-only [^11] | +| `tidb_general_log` | Not supported [^4] | Not supported [^4] | +| `tidb_generate_binary_plan` | No limitation | Read-only [^11] | +| `tidb_gogc_tuner_threshold` | No limitation | Read-only [^11] | +| `tidb_guarantee_linearizability` | No limitation | Read-only [^11] | +| `tidb_isolation_read_engines` | No limitation | Read-only [^11] | +| `tidb_log_file_max_days` | No limitation | Read-only [^11] | +| `tidb_memory_usage_alarm_ratio` | Not supported [^4] | Not supported [^4] | +| `tidb_metric_query_range_duration` | Not supported [^4] | Not supported [^4] | +| `tidb_metric_query_step` | Not supported [^4] | Not supported [^4] | +| `tidb_opt_write_row_id` | Not supported [^4] | Not supported [^4] | +| `tidb_placement_mode` | No limitation | Read-only [^11] | +| `tidb_pprof_sql_cpu` | Not supported [^4] | Not supported [^4] | +| `tidb_record_plan_in_slow_log` | Not supported [^4] | Not supported [^4] | +| `tidb_redact_log` | Not supported [^4] | Not supported [^4] | +| `tidb_restricted_read_only` | Not supported [^4] | Not supported [^4] | +| `tidb_row_format_version` | Not supported [^4] | Not supported [^4] | +| `tidb_scatter_region` | No limitation | Read-only [^11] | +| `tidb_server_memory_limit` | No limitation | Read-only [^11] | +| `tidb_server_memory_limit_gc_trigger` | No limitation | Read-only [^11] | +| `tidb_server_memory_limit_sess_min_size` | No limitation | Read-only [^11] | +| `tidb_simplified_metrics` | No limitation | Read-only [^11] | +| `tidb_slow_query_file` | Not supported [^4] | Not supported [^4] | +| `tidb_slow_log_threshold` | Not supported [^4] | Not supported [^4] | +| `tidb_slow_txn_log_threshold` | Not supported [^4] | Not supported [^4] | +| `tidb_stats_load_sync_wait` | No limitation | Read-only [^11] | +| `tidb_stmt_summary_enable_persistent` | No limitation | Read-only [^11] | +| `tidb_stmt_summary_file_max_backups` | No limitation | Read-only [^11] | +| `tidb_stmt_summary_file_max_days` | No limitation | Read-only [^11] | +| `tidb_stmt_summary_file_max_size` | No limitation | Read-only [^11] | +| `tidb_stmt_summary_filename` | No limitation | Read-only [^11] | +| `tidb_stmt_summary_history_size` | No limitation | Read-only [^11] | +| `tidb_stmt_summary_internal_query` | No limitation | Read-only [^11] | +| `tidb_stmt_summary_max_sql_length` | No limitation | Read-only [^11] | +| `tidb_stmt_summary_max_stmt_count` | No limitation | Read-only [^11] | +| `tidb_stmt_summary_refresh_interval` | No limitation | Read-only [^11] | +| `tidb_sysproc_scan_concurrency` | No limitation | Read-only [^11] | +| `tidb_top_sql_max_meta_count` | Not supported [^4] | Not supported [^4] | +| `tidb_top_sql_max_time_series_count` | Not supported [^4] | Not supported [^4] | +| `tidb_tso_client_batch_max_wait_time` | No limitation | Read-only [^11] | +| `tidb_ttl_delete_batch_size` | No limitation | Read-only [^9] | +| `tidb_ttl_delete_rate_limit` | No limitation | Read-only [^9] | +| `tidb_ttl_delete_worker_count` | No limitation | Read-only [^9] | +| `tidb_ttl_job_enable` | No limitation | Read-only [^9] | +| `tidb_ttl_job_schedule_window_end_time` | No limitation | Read-only [^9] | +| `tidb_ttl_job_schedule_window_start_time` | No limitation | Read-only [^9] | +| `tidb_ttl_running_tasks` | No limitation | Read-only [^9] | +| `tidb_ttl_scan_batch_size` | No limitation | Read-only [^9] | +| `tidb_ttl_scan_worker_count` | No limitation | Read-only [^9] | +| `tidb_txn_mode` | No limitation | Read-only [^11] | +| `tidb_wait_split_region_finish` | No limitation | Read-only [^11] | +| `tidb_wait_split_region_timeout` | No limitation | Read-only [^11] | +| `txn_scope` | No limitation | Read-only [^11] | +| `validate_password.enable` | No limitation | Always enabled [^10] | +| `validate_password.length` | No limitation | At least `8` [^10] | +| `validate_password.mixed_case_count` | No limitation | At least `1` [^10] | +| `validate_password.number_count` | No limitation | At least `1` [^10] | +| `validate_password.policy` | No limitation | Can only be `MEDIUM` or `STRONG` [^10] | +| `validate_password.special_char_count` | No limitation | At least `1` [^10] | +| `wait_timeout` | No limitation | Read-only [^11] | + +[^1]: Configuring data placement is not supported on TiDB Serverless. + +[^2]: Configuring resource groups is not supported on TiDB Serverless. + +[^3]: To perform [Back up and Restore](/tidb-cloud/backup-and-restore-serverless.md) operations on TiDB Serverless, you can use the TiDB Cloud console instead. + +[^4]: The feature is unavailable in [Security Enhanced Mode (SEM)](/system-variables.md#tidb_enable_enhanced_security). + +[^5]: To track [Slow Query](/tidb-cloud/tune-performance.md#slow-query) on TiDB Serverless, you can use the TiDB Cloud console instead. + +[^6]: To perform [Statement Analysis](/tidb-cloud/tune-performance.md#statement-analysis) on TiDB Serverless, you can use the TiDB Cloud console instead. + +[^7]: Drainer and Pump are not supported on TiDB Cloud. + +[^8]: Plugin is not supported on TiDB Serverless. + +[^9]: [Time to live (TTL)](/time-to-live.md) is currently unavailable on TiDB Serverless. + +[^10]: TiDB Serverless enforces strong password policy. + +[^11]: The variable is read-only on TiDB Serverless. diff --git a/tidb-cloud/serverless-limitations.md b/tidb-cloud/serverless-limitations.md index a49a6486bc1e8..62f16db31c6a6 100644 --- a/tidb-cloud/serverless-limitations.md +++ b/tidb-cloud/serverless-limitations.md @@ -8,49 +8,52 @@ aliases: ['/tidbcloud/serverless-tier-limitations'] -This document describes the limitations of TiDB Serverless. +TiDB Serverless works with almost all workloads that TiDB supports, but there are some feature differences between TiDB Self-Hosted or TiDB Dedicated clusters and TiDB Serverless clusters. This document describes the limitations of TiDB Serverless. We are constantly filling in the feature gaps between TiDB Serverless and TiDB Dedicated. If you require these features or capabilities in the gap, use [TiDB Dedicated](/tidb-cloud/select-cluster-tier.md#tidb-dedicated) or [contact us](https://www.pingcap.com/contact-us/?from=en) for a feature request. ## Limitations -### SQL +### Audit logs -- [Time to live (TTL)](/time-to-live.md) is not available for TiDB Serverless clusters currently. -- The [`FLASHBACK CLUSTER TO TIMESTAMP`](/sql-statements/sql-statement-flashback-to-timestamp.md) syntax is not applicable to [TiDB Serverless](/tidb-cloud/select-cluster-tier.md#tidb-serverless) clusters. -- The [`SLEEP()` function](/functions-and-operators/miscellaneous-functions.md) only supports a maximum sleep time of 300 seconds. +- [Database audit logging](/tidb-cloud/tidb-cloud-auditing.md) is currently unavailable. -### System tables +### Connection -- Tables `CLUSTER_SLOW_QUERY`, `SLOW_QUERY`, `CLUSTER_STATEMENTS_SUMMARY`, `CLUSTER_STATEMENTS_SUMMARY_HISTORY`, `STATEMENTS_SUMMARY`, `STATEMENTS_SUMMARY_HISTORY` are not available for TiDB Serverless clusters. +- Only [Public Endpoint](/tidb-cloud/connect-via-standard-connection-serverless.md) and [Private Endpoint](/tidb-cloud/set-up-private-endpoint-connections-serverless.md) can be used. You cannot use [VPC Peering](/tidb-cloud/set-up-vpc-peering-connections.md) to connect to TiDB Serverless clusters.  +- No [IP Access list](/tidb-cloud/configure-ip-access-list.md) support. -### Transaction +### Encryption -- The total size of a single transaction is set to no more than 10 MB on TiDB Serverless during the beta phase. +- Data persisted in your TiDB Serverless cluster is encrypted using the encryption tool provided by the cloud provider that manages your cluster. However, TiDB Serverless does not provide any additional optional measures for protecting data at-rest on disks beyond infrastructure-level encryption. +- Using [customer-managed encryption keys (CMEK)](/tidb-cloud/tidb-cloud-encrypt-cmek.md) is currently unavailable. -### Connection +### Maintenance window -- Only [Standard Connection](/tidb-cloud/connect-via-standard-connection-serverless.md) and [Private Endpoint](/tidb-cloud/set-up-private-endpoint-connections-serverless.md) can be used. You cannot use [VPC Peering](/tidb-cloud/set-up-vpc-peering-connections.md) to connect to TiDB Serverless clusters. -- No "IP Access List" support. +- [Maintenance window](/tidb-cloud/configure-maintenance-window.md) is currently unavailable. -### Monitoring +### Monitoring and diagnosis -- [Third-party Monitoring integrations](/tidb-cloud/third-party-monitoring-integrations.md) are currently not available for TiDB Serverless. -- [Cluster Events](/tidb-cloud/tidb-cloud-events.md) are currently not available for TiDB Serverless. -- [Built-in Alerting](/tidb-cloud/monitor-built-in-alerting.md) is currently not available for TiDB Serverless. +- [Third-party Monitoring integrations](/tidb-cloud/third-party-monitoring-integrations.md) are currently unavailable. +- [Built-in Alerting](/tidb-cloud/monitor-built-in-alerting.md) is currently unavailable. +- [Key Visualizer](/tidb-cloud/tune-performance.md#key-visualizer) is currently unavailable. +- [Index Insight](/tidb-cloud/tune-performance.md#index-insight-beta) is currently unavailable. +- [Cluster Events](/tidb-cloud/tidb-cloud-events.md) is currently unavailable. -### Diagnosis +### Self-service upgrades -- [Key Visualizer](/tidb-cloud/tune-performance.md#key-visualizer) is unavailable for TiDB Serverless. +- TiDB Serverless is a fully managed deployment of TiDB. Major and minor version upgrades of TiDB Serverless are handled by TiDB Cloud and therefore cannot be initiated by users. ### Stream data -* [Changefeed](/tidb-cloud/changefeed-overview.md) is not supported for TiDB Serverless currently. -* [Data Migration](/tidb-cloud/migrate-from-mysql-using-data-migration.md) is not supported for TiDB Serverless currently. +- [Changefeed](/tidb-cloud/changefeed-overview.md) is not supported for TiDB Serverless currently. +- [Data Migration](/tidb-cloud/migrate-from-mysql-using-data-migration.md) is not supported for TiDB Serverless currently. -### Maintenance window +### Others -- [Maintenance window](/tidb-cloud/configure-maintenance-window.md) is unavailable for TiDB Serverless. +- [Time to live (TTL)](/time-to-live.md) is currently unavailable. +- Transaction can not last longer than 30 minutes. +- For more details about SQL limitations, refer to [Limited SQL Features](/tidb-cloud/limited-sql-features.md). ## Usage quota