Oracle Partition Partition Detailed summary

This article organizes the concepts and operations of partitioned tables in the following ways: 1. Table space and the concept of partitioned Tables 2. Table partitioning's specific role 3. Table partitioning advantages and disadvantages 4. Table partitioning for several types and how to do it 5. Maintenance Operations on table partitioning. (1) Table space and partitioned table concept tablespace: is a collection of one or more data files, all of which are stored in the specified table space, but are primarily tables, so called table spaces. Partitioned tables: When the amount of data in a table grows, the query data slows down and the performance of the application degrades, so you should consider partitioning the table. After the table is partitioned, the logical table is still a complete table, but the data in the table is physically stored in multiple table spaces (physical files) so that querying the data does not always scan the entire table. (2). Table Partitioning's specific role Oracle's table partitioning capabilities bring great benefits to a wide variety of applications by improving manageability, performance, and availability. In general, partitioning can greatly improve the performance of certain queries and maintenance operations. In addition, partitioning can greatly simplify common administrative tasks, and partitioning is a key tool for building gigabytes of data systems or ultra-high availability systems. The partitioning feature can further subdivide a table, index, or index organization table into segments, where the segments of these database objects are called partitions. Each partition has its own name, and you can choose your own storage features. From the database administrator's point of view, a partitioned object has multiple segments that can be collectively managed or managed separately, which gives the database manager considerable flexibility in managing the objects after the partition. However, from the application's point of view, the partitioned table is exactly the same as the non-partitioned table, and no modifications are required to access the partitioned table using the SQL DML command. When to use partition table: 1, the size of the table is more than 2GB. 2, the table contains historical data, new data is added to the new partition. (3). Table partitioning has the following advantages: 1. Improve query performance: Queries on partitioned objects can search only the partitions they care about, improving the retrieval speed. 2. Enhanced usability: If one partition of the table fails, the data of the table in other partitions is still available; 3, maintenance convenience: If a partition of the table fails, need to repair the data, only repair the partition, 4, balanced I/O: You can map different partitions to disk to balance I/O and improve overall system performance. Cons: Partitioned table Related: Existing tables no method can be converted directly into a partitioned table. However, Oracle provides the ability to redefine tables online. (4). Table partitioning several types and how to do it

I. Scope PARTITIONING: Range partitioning maps data to each partition based on its scope, which is determined by the partition key you specify when you create the partition. This partitioning method is most commonly used, and the partitioning key often takes the date. For example, you might partition sales data by month. When using range partitioning, consider the following rules: 1. Each partition must have a values less then clause that specifies an upper value that is not included in the partition. Any record of the partition key that is equal to or greater than this upper value is added to the next higher partition. 2. All partitions, except the first one, will have an implicit lower value, which is the upper limit of the previous partition of this partition. 3. In the highest partition, MaxValue is defined. The MaxValue represents an indeterminate value. This value is higher than the value of any partition key in the other partition, and it can be understood to be higher than the value less or less that is specified in any partition, including null values. Example one: Suppose there is a customer table with data 200000 rows, we partition this table through CUSTOMER_ID, each partition stores 100000 rows, and we save each partition in a separate tablespace so that the data file can span multiple physical disks. Here is the code to create the table and partition as follows: CREATE TABLE CUSTOMER (customer_id number NOT null PRIMARY KEY, first_name VARCHAR2 () is not NULL, last_n AME VARCHAR2 (+) NOT NULL, PHONE VARCHAR2 (1) is not NULL, e-mail VARCHAR2 (+), STATUS CHAR ()) PARTITION by RANGE (customer_ ID) (PARTITION cus_part1 values less THAN (100000) tablespace cus_ts01, PARTITION cus_part2 values less THAN (200000) TAB Lespace Cus_ts02) Example II: Divide by Time CREATE TABLE order_activities (order_id number (7) Not NULL, Order_date DATE, Total_amount NUM BER, custotmer_id number (7), PAID CHAR (1)) PartitiOn by RANGE (order_date) (PARTITION ord_act_part01 VALUES less THAN (to_date (' 01-may-2003 ', ' dd-mon-yyyy ')) Tablespaceor D_ts01, PARTITION ord_act_part02 VALUES less THAN (to_date (' 01-jun-2003 ', ' dd-mon-yyyy ')) tablespace ord_ts02, PARTITION ord_act_part02 VALUES Less THAN (to_date (' 01-jul-2003 ', ' dd-mon-yyyy ') tablespace Ord_ts03) example three: MAXVALUE CREATE TABLE Ran Getable (IDD INT PRIMARY KEY, Iname VARCHAR (Ten), Grade INT) PARTITION by RANGE (grade) (PARTITION part1 VALUES less TH EN (+) tablespace part1_tb, PARTITION part2 VALUES less then (MAXVALUE) tablespace PART2_TB);

Two. List partition: This partition is characterized by a column of only a few values, based on the characteristics we can use the list partition. Example one CREATE TABLE problem_tickets (problem_id number (7) Not NULL PRIMARY KEY, DESCRIPTION VARCHAR2 (+), customer_id Numbe R (7) Not NULL, date_entered DATE NOT NULL, status VARCHAR2 ()) PARTITION by LIST (status) (PARTITION prob_active VALUES (' ACTIVE ') Tablespace prob_ts01, PARTITION prob_inactive VALUES (' INACTIVE ') tablespace prob_ts02 example two CREATE TABLE listtable (ID INT PRIMARY KEY, name VARCHAR, area VARCHAR (Ten)) PARTITION by LIST (area) (PARTITION part1 VALUES (' Guangdong ', ' Beiji Ng ') tablespace part1_tb, PARTITION part2 VALUES (' Shanghai ', ' Nanjing ') tablespace PART2_TB); )

Three. Hash partition: This type of partition uses a hash algorithm on the column values to determine which partition the row is placed in. Hash partitioning is recommended when the value of the column does not have an appropriate condition. A hash partition is a type of partition that distributes data evenly by specifying the partition number, because the partitions are identical in size by hashing on the I/O device. Example one: CREATE TABLE hash_table (col number (8), INF VARCHAR2 ()) PARTITION by HASH (COL) (PARTITION PART01 tablespace have H_ts01, PARTITION PART02 tablespace hash_ts02, PARTITION PART03 tablespace hash_ts03) Shorthand: CREATE TABLE emp (empno number (4), ename VARCHAR2 (+), Sal number) PARTITION by HASH (empno) Partitions 8 STORE in (emp1,emp2,emp3,emp4,emp5,emp6,emp 7,EMP8); Hash partition The main mechanism is based on the hash algorithm to calculate the specific record should be inserted into which partition, hash algorithm is the most important hash function, Oracle if you want to use the hash partition, only specify the number of partitions. It is recommended that the number of partitions be 2 N, which makes the data distribution more evenly between partitions.

Four. Combined range hash partition this partition is based on a range partition and a list partition, where the table is first partitioned by a column, then a list is partitioned by a column, and the partitions in the partition are called sub-partitions. CREATE TABLE SALES (product_id VARCHAR2 (5), sales_date DATE, sales_cost number, STATUS VARCHAR2 ()) PARTITION by RA NGE (sales_date) subpartition by LIST (STATUS) (PARTITION P1 VALUES less THAN (to_date (' 2003-01-01 ', ' yyyy-mm-dd ') Tablespace rptfact2009 (subpartition p1sub1 values (' ACTIVE ') tablespace rptfact2009, subpartition p1sub2 values (' Inacti VE ') tablespace rptfact2009), PARTITION P2 VALUES less THAN (to_date (' 2003-03-01 ', ' yyyy-mm-dd ')) tablespace rptfact2009 ( Subpartition p2sub1 values (' ACTIVE ') tablespace rptfact2009, subpartition p2sub2 values (' INACTIVE ') tablespace rptfact2 009))

Five. Compound-scoped Hash partition: This partition is based on a range partition and a hash partition, and the table is first scoped by a column and then hashed by a column. CREATE TABLE Dinya_test (transaction_id number primary key, item_id number (8) NOT NULL, item_description varchar2 (+), t Ransaction_date date) partition by range (transaction_date) subpartition by hash (transaction_id) Subpartitions 3 store in ( DINYA_SPACE01,DINYA_SPACE02,DINYA_SPACE03) (partition part_01 values less than (to_date (' 2006-01-01 ', ' yyyy-mm-dd ')), Partition part_02 values less than (to_date (' 2010-01-01 ', ' yyyy-mm-dd '), partition part_03 values less than (MaxValue)); (5). Some Maintenance operations on table partitioning: One, add partition the following code adds a P3 partition to the Sales table ALTER table sales add PARTITION P3 VALUES less THAN (to_date (' 2003-06-01 ', ' Yyyy-mm-dd ')); Note: The above partition boundaries should be added above the last partition bounds. The following code adds a P3SUB1 sub-partition to the P3 partition of the Sales table ALTER table Sales MODIFY PARTITION P3 add subpartition p3sub1 VALUES (' complete '); II. Delete Partition The following code removes the P3 table partition: ALTER table SALES DROP PARTITION P3; The P4SUB1 sub-partition was deleted in the following code: ALTER TABLE SALES DROP subpartition p4sub1; Note: If the deleted partition is the only partition in the table, then this partition will not be deleted and you must delete the table if you want to delete this partition. Truncate partition truncation A partition means deleting a partitionDoes not delete the partition, nor does it delete the data from the other partitions. You can truncate a table even if it has only one partition. Truncate the partition with the following code: ALTER TABLE SALES TRUNCATE PARTITION P2; Truncate the sub-partition with the following code: ALTER TABLE SALES TRUNCATE subpartition p2sub2; The merge partition merge partition merges the adjacent partition into one partition, the result partition will adopt the higher partition boundary, the notable is, cannot merge the partition to the lower boundary partition. The following code implements the merge of the P1 P2 partition: ALTER TABLE SALES Merge partitions p1,p2 into PARTITION P2; Split partition split partition divide a partition into two new partitions, after which the original partition no longer exists. Note You cannot split a hash-type partition. ALTER TABLE SALES sblit PARTITION P2 at (to_date (' 2003-02-01 ', ' yyyy-mm-dd ')] into (PARTITION p21,partition P22);

Six, join partition (COALESCA) in conjunction with partitioning is the data in the hash partition into other partitions, when the data in the hash partition is relatively large, you can increase the hash partition, and then engage, it is worth noting that the bonded partition can only be used in the hash partition. Join the partition using the following code: ALTER TABLE SALES Coalesca PARTITION;

Seven, rename table partition the following code changes P21 to P2 ALTER table SALES RENAME PARTITION P21 to P2; Viii. related queries cross-partition query select SUM (*) from (SELECT COUNT (*) cn from T_TABLE_SS PARTITION (p200709_1) union ALL SELECT COUNT (*) CN fr Om t_table_ss PARTITION (p200709_2)); How many partitions on the query table select * from User_tab_partitions WHERE table_name= ' tableName ' query index information select Object_name,object_type, Tablespace_name,sum (value) from V$segment_statistics where statistic_name in (' physical reads ', ' physical write ', ' Logical reads ') and object_type= ' INDEX ' GROUP by Object_name,object_type,tablespace_name ORDER BY 4 desc--Displays information about all partitioned tables in the database: SELECT * FROM Dba_part_tables-Displays all partition table information that the current user can access: SELECT * FROM All_part_tables--Displays information about all partitioned tables for the current user: SELECT * from User_part _tables-Display table partition information displays detailed partitioning information for all partitioned tables in the database: SELECT * FROM Dba_tab_partitions-Displays detailed partitioning information for all partitioned tables that the current user can access: SELECT * from All_tab_par Titions-Displays detailed partition information for all partition tables of the current user: SELECT * FROM User_tab_partitions-Display sub-partition information displays sub-partition information for all combined partitioned tables in the database: SELECT * FROM DBA_TAB_SUBPA Rtitions--Displays sub-partition information for all combined partitioned tables that the current user can access: SELECT * from All_tab_subPartitions--Displays sub-partition information for all the combined partition tables of the current user: SELECT * from User_tab_subpartitions--Displays the partitioning column that displays the partition column information for all partitioned tables in the database: SELECT * FROM Dba_part_k Ey_columns--Displays the partition column information for all partitioned tables that the current user can access: SELECT * FROM All_part_key_columns--Displays the partition column information for all partitioned tables of the current user: SELECT * from User_part_key_ COLUMNS-Show sub-partition column displays sub-partition column information for all partitioned tables in the database: SELECT * FROM Dba_subpart_key_columns-Displays sub-partition column information for all partitioned tables accessible by the current user: SELECT * from All_sub Part_key_columns--Displays sub-partition column information for all partitioned tables of the current user: SELECT * from User_subpart_key_columns--How to query out all partition tables in the Oracle database select * FROM User_tables a where a.partitioned= ' YES '--Deletes a table of data that is TRUNCATE TABLE table_name; --Delete partition table data for a partition is ALTER TABLE TABLE_NAME TRUNCATE PARTITION P5; PS: When update changes the partition that the data belongs to, you must give the table row movement permission. ALTER TABLE test_partition_tab enable/disable row movement; Update Partition field, change the partition, the data in the internal change is through the source data into the new partition, new data updates, the source of old data deleted steps, so rowid will change; The data index will also be re-run.

Oracle Partition Partition Detailed summary