From be2e1bbb9da353e9b76bab2b06712948f9397d6b Mon Sep 17 00:00:00 2001 From: yikeke Date: Tue, 30 Jun 2020 11:46:30 +0800 Subject: [PATCH 1/4] integrate tiflash faq into tidb-faq.md and add aliases --- faq/tidb-faq.md | 24 +++++++++++++++++++++++- tiflash/tiflash-faq.md | 30 ------------------------------ 2 files changed, 23 insertions(+), 31 deletions(-) delete mode 100644 tiflash/tiflash-faq.md diff --git a/faq/tidb-faq.md b/faq/tidb-faq.md index dc03f1b848096..b7fb742017cb2 100644 --- a/faq/tidb-faq.md +++ b/faq/tidb-faq.md @@ -2,7 +2,7 @@ title: TiDB FAQ summary: Learn about the most frequently asked questions (FAQs) relating to TiDB. category: faq -aliases: ['/docs/dev/faq/tidb-faq/','/docs/dev/faq/tidb/'] +aliases: ['/docs/dev/faq/tidb-faq/','/docs/dev/faq/tidb/','/docs/dev/tiflash/tiflash-faq/','/docs/dev/reference/tiflash/faq/','/tidb/dev/tiflash-faq'] --- # TiDB FAQ @@ -730,6 +730,28 @@ The memory usage of TiKV mainly comes from the block-cache of RocksDB, which is No. TiDB (or data created from the transactional API) relies on a specific key format. It is not compatible with data created from RawKV API (or data from other RawKV-based services). +### Manage the TiFlash server + +#### Does TiFlash support direct writes? + +Currently, TiFlash does not support direct writes. You can only write data to TiKV, and then replicate the data to TiFlash. + +#### How can I estimate the storage resources if I want to add TiFlash to an existing cluster? + +You can evaluate which tables might require acceleration. The size of a single replica of these tables data is roughly equal to the storage resources required by two replicas of TiFlash. Note that you need to take into account the free space required. + +#### How can data in TiFlash be highly available? + +TiFlash restores data through TiKV. As long as the corresponding Regions in TiKV are available, TiFlash can restore data from these Regions. + +#### How many replicas does TiFlash recommend to set up? + +If you need highly available TiFlash services (rather than highly available data), it is recommended to set up two replicas for TiFlash. If you allow TiKV replicas to provide analytical services when TiFlash is down, you can set up a single TiFlash replica. + +#### Should I use TiSpark or TiDB server for a query? + +It is recommended to use TiDB server if you query a single table mainly using filtering and aggregation, because the TiDB server has better performance on the columnar storage. It is recommended to use TiSpark if you query a table mainly using joins. + ### TiDB test #### What is the performance test result for TiDB using Sysbench? diff --git a/tiflash/tiflash-faq.md b/tiflash/tiflash-faq.md deleted file mode 100644 index 9c9e40f06907b..0000000000000 --- a/tiflash/tiflash-faq.md +++ /dev/null @@ -1,30 +0,0 @@ ---- -title: TiFlash FAQ -summary: Learn the frequently asked questions (FAQs) and answers about TiFlash. -category: faq -aliases: ['/docs/dev/tiflash/tiflash-faq/','/docs/dev/reference/tiflash/faq/'] ---- - -# TiFlash FAQ - -This document lists the frequently asked questions (FAQs) and answers about TiFlash. - -## Does TiFlash support direct writes? - -Currently, TiFlash does not support direct writes. You can only write data to TiKV, and then replicate the data to TiFlash. - -## How can I estimate the storage resources if I want to add TiFlash to an existing cluster? - -You can evaluate which tables might require acceleration. The size of a single replica of these tables data is roughly equal to the storage resources required by two replicas of TiFlash. Note that you need to take into account the free space required. - -## How can data in TiFlash be highly available? - -TiFlash restores data through TiKV. As long as the corresponding Regions in TiKV are available, TiFlash can restore data from these Regions. - -## How many replicas does TiFlash recommend to set up? - -If you need highly available TiFlash services (rather than highly available data), it is recommended to set up two replicas for TiFlash. If you allow TiKV replicas to provide analytical services when TiFlash is down, you can set up a single TiFlash replica. - -## Should I use TiSpark or TiDB server for a query? - -It is recommended to use TiDB server if you query a single table mainly using filtering and aggregation, because the TiDB server has better performance on the columnar storage. It is recommended to use TiSpark if you query a table mainly using joins. From e9a9b582c7d40eeda3e788c048d88e11454a0aef Mon Sep 17 00:00:00 2001 From: yikeke Date: Tue, 30 Jun 2020 11:48:09 +0800 Subject: [PATCH 2/4] Update TOC.md --- TOC.md | 1 - 1 file changed, 1 deletion(-) diff --git a/TOC.md b/TOC.md index d06064b0dbab1..5c7321c435d56 100644 --- a/TOC.md +++ b/TOC.md @@ -406,7 +406,6 @@ + TiFlash + [Overview](/tiflash/tiflash-overview.md) + [Use TiFlash](/tiflash/use-tiflash.md) - + [FAQ](/tiflash/tiflash-faq.md) + TiUP + [Overview](/tiup/tiup-overview.md) + [Manage TiUP Components](/tiup/manage-tiup-component.md) From 75c3b6f17f6332416b1330214adea77356313596 Mon Sep 17 00:00:00 2001 From: yikeke Date: Tue, 30 Jun 2020 12:05:26 +0800 Subject: [PATCH 3/4] align https://github.com/pingcap/docs-cn/pull/3176/files --- troubleshoot-tidb-lightning.md | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/troubleshoot-tidb-lightning.md b/troubleshoot-tidb-lightning.md index cfa02fc5a67b3..0b93d8ed47241 100644 --- a/troubleshoot-tidb-lightning.md +++ b/troubleshoot-tidb-lightning.md @@ -141,3 +141,11 @@ See the [Checkpoints control](/tidb-lightning/tidb-lightning-checkpoints.md#chec 3. Ensure the entire cluster is using the same and latest version of `tzdata` (version 2018i or above). On CentOS, run `yum info tzdata` to check the installed version and whether there is an update. Run `yum upgrade tzdata` to upgrade the package. + +## `[Error 8025: entry too large, the max entry size is 6291456]` + +**Cause**: A single row of key-value pairs generated by TiDB Lightning exceeds the limit set by TiDB. + +**Solution**: + +Currently, the limitation of TiDB cannot be bypassed. You can only ignore this table to ensure the successful import of other tables. From 76355de1071348213fc01f8cc2e17c5289588c6e Mon Sep 17 00:00:00 2001 From: Keke Yi <40977455+yikeke@users.noreply.github.com> Date: Tue, 30 Jun 2020 15:10:40 +0800 Subject: [PATCH 4/4] Apply suggestions from code review Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com> --- faq/tidb-faq.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/faq/tidb-faq.md b/faq/tidb-faq.md index b7fb742017cb2..e6f986bf77c64 100644 --- a/faq/tidb-faq.md +++ b/faq/tidb-faq.md @@ -744,7 +744,7 @@ You can evaluate which tables might require acceleration. The size of a single r TiFlash restores data through TiKV. As long as the corresponding Regions in TiKV are available, TiFlash can restore data from these Regions. -#### How many replicas does TiFlash recommend to set up? +#### How many replicas are recommended for TiFlash? If you need highly available TiFlash services (rather than highly available data), it is recommended to set up two replicas for TiFlash. If you allow TiKV replicas to provide analytical services when TiFlash is down, you can set up a single TiFlash replica.