Done!
-- 此致！Best Regards 陈明雨 Mingyu Chen Email: morning...@apache.org 在 2022-06-24 08:48:29，"Chen Zhang" <chzhang1...@gmail.com> 写道： >@Mingyu, my username: zhannngchen. Thanks~ > >Best >Chen Zhang >On Jun 24, 2022, 00:56 +0800, 陈明雨 <morning...@163.com>, wrote: >> Hi Zhang Chen: >> I have created a DSIP-018 for this[1]. But you need to create an account and >> tell me your username. >> >> >> [1] >> https://cwiki.apache.org/confluence/display/DORIS/DSIP-018%3A+Support+Merge-On-Write+implementation+for+UNIQUE+KEY+data+model >> >> >> >> >> -- >> >> 此致！Best Regards >> 陈明雨 Mingyu Chen >> >> Email: >> morning...@apache.org >> >> >> >> >> >> At 2022-06-23 22:29:49, "Chen Zhang" <chzhang1...@gmail.com> wrote: >> > @Minghong We'll use a multi-version delete bitmap, only save delta for >> > each version. >> > For example, we have a rowset with version [0-98], transaction 99 updated >> > some row in that rowset, and so does transaction 100 and 101, there would >> > be 3 delete bitmaps on that rowset, corresponding to rows updated by >> > version 99, 100 and 101. A query with version x will only see the bitmap >> > up to version x. There's more details about space saving and cache >> > acceleration, let's discuss it in DSIP. >> > >> > @Xiaoli, our team have finished most develop works for the basic function >> > in our private repository, but there‘s still lots of works to do, welcome >> > to get involve. >> > >> > @Mingyu, could you help to create a DISP doc? I don't seem to have >> > permission. >> > >> > Best >> > Chen Zhang >> > On Jun 23, 2022, 21:41 +0800, Zhou Minghong <minghong.z...@163.com>, wrote: >> > > Hi Chen Zhang >> > > one question about "and a delete bitmap (marks some rowid as deleted)”： >> > > how to handle transaction information by a bitmap? >> > > for example, transaction_100 delete a row, but this still visible to >> > > transaction_99, but not visible to trasanction_101. How to handle this >> > > case? >> > > >> > > >> > > Br/Minghong >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > At 2022-06-23 19:14:58, "Zhu,Xiaoli" <zhuxiaol...@baidu.com> wrote: >> > > > Hi Chen Zhang, >> > > > >> > > > I am very interested in this topic, and want to participate in the >> > > > development. >> > > > >> > > > 在 2022/6/23 下午2:44，“Chen Zhang”<chzhang1...@gmail.com> 写入: >> > > > >> > > > Hi devs, >> > > > >> > > > Unique-Key data model is widely used in scenarios like Flink-CDC, user >> > > > profile(用户画像), E-commerce orders, but the query performance for current >> > > > Merge-On-Read implementation is not good, due to the following reasons: >> > > > >> > > > 1. Doris can't determine whether one row in a segment file is latest or >> > > > outdated, so it has to do some extra merge sort before getting the >> > > > latest data, and key comparison is quite CPU-costive. >> > > > 2. Aggregate function predicate push down is not supported by the >> > > > Unique-Key data model due to reason(1). >> > > > >> > > > I'd like to propose to support a Merge-On-Write implementation for the >> > > > Unique-Key data model, which leverages a new segment-file-level primary >> > > > key index (used for point lookup on write) and a delete bitmap (marks >> > > > some >> > > > rowid as deleted), which can optimize read performance significantly. >> > > > >> > > > At the beginning, we wanted to add another Primary-Key data model with >> > > > Merge-On-Write implementation, but after a lot of discussion, we'd >> > > > prefer >> > > > to improve the Unique-Key data model rather than adding another one. >> > > > >> > > > I'll add detailed design and related research in the DSIP doc later. >> > > > >> > > > >> > > > --------------------------------------------------------------------- >> > > > To unsubscribe, e-mail: dev-unsubscr...@doris.apache.org >> > > > For additional commands, e-mail: dev-h...@doris.apache.org >> > > >
