PostgreSQL provides a number of system management functions to view tables, indexes, table spaces, and the size of the database, described in detail below.
second, the Database object dimension function
The name of the function
The number of bytes requi
database backup and recovery)Copy the data using the Copy command:E:\>pg_dump-u Postgres Testdb1>testdb14.sql The data is copied using the INSERT statement:E:\>pg_dump-u Postgres--column-inserts Testdb1>testdb15.sql 4. Migrating the CPOST database structure on PostgreSQL
bytesDouble precision 15-bit decimal digit Precision 8 bytes3. Arbitrary precision TypeThe use of numeric in PostgreSQL means that a type of arbitrary precision is a numeric value, denoted by numeric (m,n), where m is called precision and represents the total number of digits; n is known as the scale, which is the number of digits representing decimals. For example: 563.129 with a precision of 9 and a scale of 3Note: The valid range of values for num
tutorial, without encountering any problems. 2. In fact, this homework is very simple, but at the beginning I very blindly began to do homework, have not made clear the principle, encountered what attributes to convert what file and import into the database. Then the data were all erased, first understand tpc-h sql statements, with particular emphasis on the order in which statements are executed, beca
Deadline data cannot be imported into the postgresql database solution after statisticgathering is configured in deadline and saved to postgresql, slave and job information cannot be saved to postgresql during rendering tasks, and metadata. Wouldyouliketoadd is prompted when
To back up the database:pg_dump-h localhost-u root demo02 >/home/arno/dumps/demo02.bakTo recover a database:psql-h localhost-u root-d Demo Backup table:pg_dump-h localhost-u root demo02-t books >/home/arno/dumps/books.bakRecovery table:psql-h localhost-u root-d demo-t Books Psql Copy to/from usage:1. Need to log in to the database using Postgres Super User psql-u postgres-d demo022. Saved/Read folders need to give Postgres user permission to read and
PostgreSQL-based scalable, open-source Big Data cluster database: POSTGRES-XLhttp://www.postgres-xl.org/Postgres's-XL is a scale-out open source SQL database cluster based on the PostgreSQL database, with sufficient flexibility to
Label:When we use the PostgreSQL database, if a table is not constrained, it is likely that there will be several identical pieces of data, that is, duplicate data. As shown in the following:So what if we were to delete 2 of them? The first is that we can clear the contents of the table, and then insert the content int
PostgreSQL Advantage2016-10-20 21:36 686 People read comments (0) favorite reports Classification:MySQL Database (5)PostgreSQL is a free object-relational database server (database management system), which is very powerful. Includes support for the world's richest
There are many ways to do this, and the method used here is more secure. Then there will be time to add another method.The method is divided into three steps: Backing up data, creating a new table structure, importing dataBackup data: >>\copy table_name to '/home/bak/table_name.sql ';Create a new table structure: Copy the SQL statements from the original table structure, delete unnecessary and inappropriate
, indexing is 35% faster than indexing first
When logging is not logged, indexing is slightly faster than indexing first, but not very different
The fastest combination of insert data is:unlogged table + multithreaded Batch insert+ post-build index Guess:During the insert process, the time it takes to maintain the index is 35% to 40% of the total time, and it is mainly spent on log persistence. Other:At the same time, some other indicators i
PostgreSQL database data simple import and export Blog categories:
Postgres Command operation:Data export: Pg_dump-u postgres (user name) (-t table name) database name (default with username) > C:\fulldb.sqlImport of dat
PostgreSQL 9.4 is loading a new feature called JSONB, a new type of data that can store JSON data that supports gin indexes. In other words, this feature, in the upcoming update, most importantly, if this is not important, then put Postgres in the file as the recommended location for the database system.
Since 9.2, a
Sample captured data
Example of the generated document
Objectives and objectives of database Engineering
Task Description and database system Purpose
Description of the main user view (inc
the tableDevice_no,Btn_no,FlagData_time timestamp "Yyyy-mm-dd hh24:mi:ss"--format conversion with timestamp "Yyyy-mm-dd hh24:mi:ss" because the field type in the datasheet is a date type, not a literal type )2.Execute the SQLLDR command in cmd as follows Sqlldr Userid=manpowertest/[email protected] Control=c:\andon.ctl Log=c:\andon.logArchive 1:andon.txt Building number, device number, button code, switch status, trigger time a2-1,4,2,1,2014-10-29 15:14:13a2-1,30,2,0,2014-10-29 14:51:36a2-2,10
PHP excel sample code for downloading (retrieving data from a database)
* Generate an excel file in PHPEXCEL
* @ Author: firmy
* @ Desc supports generating excel files for any row and column data without adding cell styles and alignment.
Header ("connect-type: text/html; charset = utf-8 ");
$ Dsn = "mysql: hos
PostgreSQL database server listener settings and Client Connection Methods tutorial, postgresql Server
As we all know, PostgreSQL is a free object-relational database server (Database Management System). It is an open-source
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