partitioning

Oracle SQL: Selecting data and partition name from table and truncating partitions

由 。_饼干妹妹 提交于 2019-12-21 05:22:20
问题 This is a two part question: 1) Is it possible to retrieve the name of the partition that data lives in using a select statement, based on its ROWID or some other identifier? eg. SELECT DATA_ID, CATEGORY, VALUE, **PARTITION_NAME** FROM MYTABLE WHERE CATEGORY = 'ABC' 2) Is it possible to truncate a single partition of a table, without deleting the data stored in the other partitions? I have a table with over a billion rows, hash partitioned by category. Only a handful of the categories have

Object Positioning Algorithm

由 守給你的承諾、 提交于 2019-12-21 04:52:43
问题 I'm wondering if there is an "optimal" solution for this problem: I have a n x m (pixel) sized space with p preexisting rectangled - objects in various sizes on it. Now I want to place q (same sized) new objects in this space without any overlapping. The algorithm I came up with: Create array A[][] with the size [(n)/(size_of_object_from_q)]x[(n)/(size_of_object_from_q)] Iterate all Elements from p and for each: mark all fields in A[][] as occupied, where the element "lies" Place all elements

How many table partitions is too many in Postgres?

由 て烟熏妆下的殇ゞ 提交于 2019-12-20 11:14:36
问题 I'm partitioning a very large table that contains temporal data, and considering to what granularity I should make the partitions. The Postgres partition documentation claims that "large numbers of partitions are likely to increase query planning time considerably" and recommends that partitioning be used with "up to perhaps a hundred" partitions. Assuming my table holds ten years of data, if I partitioned by week I would end up with over 500 partitions. Before I rule this out, I'd like to

history rows management in database

由 守給你的承諾、 提交于 2019-12-20 10:05:14
问题 As in many databases, i am designing a database that should keep record of previous versions of the rows changed in each table. The standard solution to this problem is to keep a history table for each data table, and whenever a row needs to be updated in the data table, a copy of the current row gets inserted to the history table and than the row in the data table gets updated. the disadvantages of this solution for me: maintenance of 2 tables instead of 1, (in case the structure of the

Kafka Streams - How to better control partitioning of internally created state store topic?

由 六眼飞鱼酱① 提交于 2019-12-20 05:45:32
问题 State stores in Kafka Streams are created internally. State stores are partitioned by key, but do not allow to provide partitioning other than by key (to my knowledge). QUESTIONS How to control the number of partitions of a state-store internally created topic ? How does the state store topic infer the number of partitions and the partitioning to use by default, and how to override? How to work it around if you want to partition your state-store by something other than the key of your

Hive: Add partitions for existing folder structure

由 夙愿已清 提交于 2019-12-20 05:32:10
问题 I have a folder structure in HDFS like below. However, no partitions were actually created on the table using the ALTER TABLE ADD PARTITION commands, even though the folder structure was setup as if the table had partitions. How can I automatically add all the partitions to the Hive table? (Hive 1.0, external table) /user/frank/clicks.db /date=20190401 /file0004.csv /date=20190402 /file0009.csv /date=20190501 /file0000.csv /file0001.csv ...etc 回答1: Use msck repair table command: MSCK [REPAIR]

Mysql table partition based on last digit of a column/id

由 蓝咒 提交于 2019-12-20 02:56:21
问题 I want to create partitions based on last digit of employee id, i.e all ids ending with 0 go to first partition , ending with 1 go to second partition and so on.. This way I want to create 10 partitions, employee id can be int or varchar which ever is easy and fast in making partition. Currently we have 10 separate tables employee_01, employee_02... (dont like this) Although the retrieval and insertion time will be enhanced by no means, but maintainability would be increased by huge factors,

Is it possible to partially refresh a materialized view in Oracle?

由 ￣綄美尐妖づ 提交于 2019-12-19 05:21:15
问题 I have a very complex Oracle view based on other materialized views, regular views as well as some tables (I can't "fast refresh" it). Most of the time, existing records in this view are based on a date and are "stable", with new record sets having new dates. Occasionally, I receive back-dates. I know what those are and how to deal with them if I were maintaining a table, but I would like to keep this a "view". A complete refresh would take around 30 minutes, but it only takes 25 seconds for

Get all possible partitions of a set

由 耗尽温柔 提交于 2019-12-19 03:18:04
问题 In Java I have a set where I want to obtain all possible combinations of subsets which their union make the main set. (partitioning a set) for example, given: set={1,2,3} the result should be: { {{1,2,3}} , {{1},{2,3}} , {{1,2},{3}} , {{1,3},{2}}, {{1},{2},{3}}} the number of possible partition of a set of n elements is B(n) known as Bell number. The code so far: public static <T> Set<Set<T>> powerSet(Set<T> myset) { Set<Set<T>> pset = new HashSet<Set<T>>(); if (myset.isEmpty()) { pset.add

oracle patition 分区和索引

由 巧了我就是萌 提交于 2019-12-18 19:16:46
【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> oracle patition 分区 参考博文 http://docs.oracle.com/cd/B10501_01/server.920/a96524/c12parti.htm#460945 简单的分区方法是 Hash Partitioning Hash partitioning enables easy partitioning of data that does not lend itself to range or list partitioning. It does this with a simple syntax and is easy to implement. It is a better choice than range partitioning when: You do not know beforehand how much data maps into a given range The sizes of range partitions would differ quite substantially or would be difficult to balance manually Range partitioning would cause the data to be
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