Oh, that's easier than tombstones. flag is_deleted and update timestamp (so it gets pulled again).
On Tue, Apr 6, 2021 at 10:48 AM Tijo Thomas <tijothoma...@gmail.com> wrote: > Abhishek, > Good point. Do we need one more col for storing if it's deleted or not? > > On Tue, Apr 6, 2021 at 4:32 PM Abhishek Agarwal <abhishek.agar...@imply.io > > > wrote: > > > If an entry is deleted from the metadata, how is the coordinator going to > > update its own state? > > > > On Tue, Apr 6, 2021 at 3:38 PM Itai Yaffe <itai.ya...@gmail.com> wrote: > > > > > Hey, > > > I'm not a Druid developer, so it's quite possible I'm missing many > > > considerations here, but from a first glance, I like your offer, as it > > > resembles the *tsColumn *in JDBC lookups ( > > > > > > > > > https://druid.apache.org/docs/latest/development/extensions-core/lookups-cached-global.html#jdbc-lookup > > > ). > > > > > > Anyway, just my 2 cents. > > > > > > Thanks! > > > Itai > > > > > > On Tue, Apr 6, 2021 at 6:07 AM Benedict Jin <asdf2...@apache.org> > wrote: > > > > > > > Hi all, > > > > > > > > Recently, when the Coordinator in our company's Druid cluster pulls > > > > metadata, there is a performance bottleneck. The main reason is the > > huge > > > > amount of metadata, which leads to a very slow process of scanning > the > > > full > > > > table of metadata storage and deserializing metadata. The size of the > > > full > > > > metadata has been reduced through TTL, Compaction, Rollup, and etc., > > but > > > > the effect is not very significant. Therefore, I want to design a > > scheme > > > > for Coordinator to pull metadata incrementally, that is, each time > > > > Coordinator only pulls newly added metadata, so as to reduce the > query > > > > pressure of metadata storage and the pressure of deserializing > > metadata. > > > > The general idea is to add a column last_update to the druid_segments > > > table > > > > to record the update time of each record. Furthermore, when we query > > the > > > > metadata table, we can add filter conditions for the last_update > column > > > to > > > > avoid full table scan operations. Moreover, whether it is MySQL or > > > > PostgreSQL as the metadata storage medium, it can support > > > > automatic update of the timestamp field, which is somewhat similar > to > > > the > > > > characteristics of triggers. So, have you encountered this problem > > > before? > > > > If so, how did you solve it? In addition, do you have any suggestions > > or > > > > comments on the above incremental acquisition of metadata? Please let > > me > > > > know, thanks a lot. > > > > > > > > Regards, > > > > Benedict Jin > > > > > > > > --------------------------------------------------------------------- > > > > To unsubscribe, e-mail: dev-unsubscr...@druid.apache.org > > > > For additional commands, e-mail: dev-h...@druid.apache.org > > > > > > > > > > > > > > > > -- > Thanks & Regards > Tijo Thomas >
