Hi, I have updated the FLIP. Please check again. If there are no other concerns, I will start voting. Thank you all for your support!
Best regards, Jing On Fri, Jul 22, 2022 at 1:32 PM Jing Ge <j...@ververica.com> wrote: > Thanks Jark, fair enough, I will update the FLIP accordingly. > > Best regards, > Jing > > On Fri, Jul 22, 2022 at 6:07 AM Jark Wu <imj...@gmail.com> wrote: > >> Hi Jing, >> >> I have some concerns about the isBulkGetSupported() approach. >> 1. Catalog developers need to learn the contract between >> `isBulkGetSupported()` and bulk get methods >> 2. The contract of isBulkGetSupported() is fragile. Because developers may >> forget to override >> `isBulkGetSupported` and be confused the implemented bulk methods are >> not called. >> 3. It's not extensible when we have more bulk methods in future releases. >> >> I have discussed with Godfrey offline and come up with (maybe) a better >> solution. >> The default implementation of bulk methods should iterate on the single >> get >> method and wrap the result. >> In this way, the planner can always call the bulk methods no matter >> whether >> the Catalog implements the bulk method or not. >> This can also address the above concerns. >> >> What do you think? >> >> Best, >> Jark >> >> >> >> >> >> On Thu, 21 Jul 2022 at 21:13, Jing Ge <j...@ververica.com> wrote: >> >> > Thanks Jingsong and Jark. I will create another FLIP to cover the >> > optimization topic that partitions and partition stats could be fetched >> > from catalog in one single call. >> > >> > Thanks for the hint w.r.t. the compatibility issue. I have updated the >> FLIP >> > to provide all methods as default interface methods. A new >> > method isBulkGetSupported() has been added. Would you like to take a >> look >> > at it again? >> > >> > Best regards, >> > Jing >> > >> > On Wed, Jul 20, 2022 at 11:23 AM Jark Wu <imj...@gmail.com> wrote: >> > >> > > I agree with Jingsong. >> > > >> > > There are use cases to get partitions and partition stats in a single >> > call >> > > to reduce the IO cost. >> > > For example, extending Catalog#listPartitions to >> > > Catalog#listPartitionsWithStats, >> > > and extending Catalog#listPartitionsByFilter to >> > > Catalog#listPartitionsWithStatsByFilter. >> > > This allows the planner to choose the cheapest one to request >> partitions >> > > and stats. >> > > But of course, this can be introduced in the future. >> > > >> > > Besides, I found that the FLIP doesn't cover compatibility properly. >> > > Introducing two new methods in Catalog >> > > will break all third-party catalog implementations. On the other hand, >> > the >> > > planner should >> > > have a way to identify whether the Catalog supports bulk get. >> > > >> > > Best, >> > > Jark >> > > >> > > On Wed, 20 Jul 2022 at 16:43, Jingsong Li <jingsongl...@gmail.com> >> > wrote: >> > > >> > > > Thanks for your reply. >> > > > >> > > > - Consider bulkGetPartitionStatistics, partition statistics are >> > > > already in HiveMetastoreClient.listPartitions. But on our side, we >> > > > need Catalog.getPartitions first, and then >> > > > Catalog.bulkGetPartitionStatistics. >> > > > >> > > > - Consider bulkGetPartitionColumnStatistics, yes, as you said, we >> need >> > > it. >> > > > >> > > > But to unify them, the current FLIP is acceptable. >> > > > >> > > > Best, >> > > > Jingsong >> > > > >> > > > On Wed, Jul 20, 2022 at 3:57 PM Jing Ge <j...@ververica.com> wrote: >> > > > > >> > > > > Hi Jingsong, >> > > > > >> > > > > Thanks for clarifying it. Are you suggesting a new method or >> changing >> > > the >> > > > > name of the methods described in the FLIP? >> > > > > Please see my answers and further questions below. >> > > > > >> > > > > Best regards, >> > > > > Jing >> > > > > >> > > > > On Wed, Jul 20, 2022 at 4:28 AM Jingsong Li < >> jingsongl...@gmail.com> >> > > > wrote: >> > > > > >> > > > > > Hi Jing, >> > > > > > >> > > > > > I understand that the statistics for partitions are currently >> only >> > > > > > used by Hive, so we can look at the Hive implementation: >> > > > > > >> > > > > > See HiveCatalog.getPartitionStatistics. >> > > > > > To get the statistics, we actually get them from the >> > > > > > org.apache.hadoop.hive.metastore.api.Partition object. >> > > > > > >> > > > > >> > > > > Correct. Both new methods will do the same thing but in bulk mode. >> > > > > >> > > > > >> > > > > > >> > > > > > According to HiveMetastore's API, partition-related operations >> > > > > > actually get the partition as well as the statistics >> information. >> > > > > > >> > > > > >> > > > > I am not really sure which API it is. Methods in >> HiveMetaStoreClient >> > > that >> > > > > are dealing with partitions will either return partitions or >> > > > statisticObjs, >> > > > > e.g. listPartitions(...) or getPartitionColumnStatistics(...) >> > > > > >> > > > > >> > > > > > >> > > > > > So if the current partition statistics are just for Hive, can we >> > > > > > consider unifying it with Hive? >> > > > > > >> > > > > >> > > > > Yes, we are on the same page. This FLIP is trying to unify it with >> > > > > HiveMetaStoreClient. >> > > > > >> > > > > >> > > > > > >> > > > > > For example, in PushPartitionIntoTableSourceScanRule, just use >> > > > > > `listPartitionWithStats`, and adjust table statistics from >> > > partitions. >> > > > > > >> > > > > >> > > > > Does the bulkGetPartitionStatistics work in this case too? Or, do >> you >> > > > mean >> > > > > you need both partitions and related statistics returned by a new >> > > method >> > > > > called `listPartitionWithStats`? >> > > > > >> > > > > >> > > > > > Best, >> > > > > > Jingsong >> > > > > > >> > > > > > On Tue, Jul 19, 2022 at 8:44 PM Jing Ge <j...@ververica.com> >> > wrote: >> > > > > > > >> > > > > > > Thanks Jingsong for the suggestion. >> > > > > > > >> > > > > > > Do you mean using a different naming convention? There is a >> > thought >> > > > and >> > > > > > > description in the FLIP about using "list" or "bulkGet": >> > > > > > > >> > > > > > > - bulkGetPartitionStatistics(...) has been chosen over >> > > > > > > listPartitionStatistics(...), because, comparing to >> database >> > and >> > > > > > partition >> > > > > > > that are static and can be listed, statistics are more >> dynamic >> > > and >> > > > > > will >> > > > > > > need more computation logic to create, therefore using >> "get" >> > is >> > > > > > > semantically more feasible than list. The "bulk" gives >> users >> > the >> > > > hint >> > > > > > that >> > > > > > > this method will work in the bulk mode and return a >> collection >> > > of >> > > > > > instances. >> > > > > > > >> > > > > > > >> > > > > > > As a reference, we can see that no method in MetaStoreClient, >> > that >> > > > > > > calculates statistics, uses the "list" naming convention. >> > > > > > > >> > > > > > > Best regards, >> > > > > > > Jing >> > > > > > > >> > > > > > > On Fri, Jul 15, 2022 at 5:38 AM Jingsong Li < >> > > jingsongl...@gmail.com> >> > > > > > wrote: >> > > > > > > >> > > > > > > > Thanks for starting this discussion. >> > > > > > > > >> > > > > > > > Have we considered introducing a listPartitionWithStats() in >> > > > Catalog? >> > > > > > > > >> > > > > > > > Best, >> > > > > > > > Jingsong >> > > > > > > > >> > > > > > > > On Fri, Jul 15, 2022 at 10:08 AM Jark Wu <imj...@gmail.com> >> > > wrote: >> > > > > > > > > >> > > > > > > > > Hi Jing, >> > > > > > > > > >> > > > > > > > > Thanks for starting this discussion. The bulk fetch is a >> > great >> > > > > > > > improvement >> > > > > > > > > for the optimizer. >> > > > > > > > > The FLIP looks good to me. >> > > > > > > > > >> > > > > > > > > Best, >> > > > > > > > > Jark >> > > > > > > > > >> > > > > > > > > On Fri, 8 Jul 2022 at 17:36, Jing Ge <j...@ververica.com> >> > > wrote: >> > > > > > > > > >> > > > > > > > > > Hi devs, >> > > > > > > > > > >> > > > > > > > > > After having multiple discussions with Jark and >> Goldfrey, >> > I'd >> > > > like >> > > > > > to >> > > > > > > > start >> > > > > > > > > > a discussion on the mailing list w.r.t. FLIP-247[1], >> which >> > > will >> > > > > > > > > > significantly improve the performance by providing the >> bulk >> > > > fetch >> > > > > > > > > > capability for table and column statistics. >> > > > > > > > > > >> > > > > > > > > > Currently the statistics information about tables can >> only >> > be >> > > > > > fetched >> > > > > > > > from >> > > > > > > > > > the catalog by each given partition iteratively. Since >> > > getting >> > > > > > > > statistics >> > > > > > > > > > information from catalogs is a very heavy operation, in >> > order >> > > > to >> > > > > > > > improve >> > > > > > > > > > the query performance, we’d better provide >> functionality to >> > > > fetch >> > > > > > the >> > > > > > > > > > statistics information of a table for all given >> partitions >> > in >> > > > one >> > > > > > shot. >> > > > > > > > > > >> > > > > > > > > > Based on the manual performance test, for 2000 >> partitions, >> > > the >> > > > cost >> > > > > > > > will be >> > > > > > > > > > improved from 10s to 2s. The improvement result is 500%. >> > > > > > > > > > >> > > > > > > > > > [1] >> > > > > > > > > > >> > > > > > > > > > >> > > > > > > > >> > > > > > >> > > > >> > > >> > >> https://cwiki.apache.org/confluence/display/FLINK/FLIP-247%3A+Bulk+fetch+of+table+and+column+statistics+for+given+partitions >> > > > > > > > > > >> > > > > > > > > > Best regards, >> > > > > > > > > > Jing >> > > > > > > > > > >> > > > > > > > >> > > > > > >> > > > >> > > >> > >> >
