Function Introduction
POSTGRES-XC/XL/X2 is an open source project. It provides a multiple-master synchronous, transparent, PostgreSQL cluster solution. Unlike other cluster tools, it has a strong scalability when writing data, and introduces the concept of cluster environment with multiple master architectures. Multi-master means that when writing data, it is no longer subject to a single master node and will be well improved in writing speed.
: maxspeed:winter=* means the maximum speed limit in winter
Postgressql Database Installation
Open source free database: PostgreSQL Download Installation Tutorial _ Baidu Experience OSM data Extraction
Download Osm:http://dev.openstreetmap.org/~bretth/osmosis-build/osmosis-latest.zipdownload China map dataHttp://download.geofabrik.de/asia/china.html
Data cropping
Regional cut, cut the map of China into Wuhan map:
Osmosis--READ-PBF file= "CHINA-LATEST.OSM.PBF"--used-node--bounding-box left=113.9
Transferred from: http://blog.csdn.net/yufenghyc/article/details/45869509--1 Examplepostgres=# Select 1/4;? column?----------0(1 row)In PG If you want to do division and want to keep decimals, the method above does not work, because the "/" Operation results are rounded, and the fractional part is truncated.--2 Type Conversionspostgres=# Select round (1:: Numeric/4:: Numeric,2);Round-------0.25(1 row)Note: After the type conversion, you can retain the fractional part.--3 can also be converted by
selectextract (ISOYEAR fromfromdate_) asyear_,--the year in which the week was made extract (WEEKFROM fromdate_) asweek_,--the year in which the week was made To_char (fromDate _, ' YYYYMMDD ') asfromdate_,--Week start date to_char (todate_, ' YYYYMMDD ') as End date of todate_--week from (select (date (curDate) -7*weeks_) asfromDate_, (date (curdate) -7*weeks_+6) as toDate_from (selectgenerate_series (1,100) weeks_, -- interval weeks (sequence, here take 100 weeks) cast (Date_trunc (' Week ',
That blue students:http://blog.163.com/li_hx/ Have the ideal pig:Http://my.oschina.net/quanzl Tangcheng (OSDBA): http://blog.osdba.net/ Sun Peng:http://blog.sciencenet.cn/home.php?mod=spaceuid=419883 Big belly Bear:http://www.cnblogs.com/daduxiong/category/257029.html Stephen_liu:http://www.cnblogs.com/stephen-liu74/archive/2012/06/08/2315679.html Note: Ranked in no particular order, after finding the right blog to add. --5 Video Tutorial PostgreSQL video Tutorial (with):http://www.tudou.com/ho
1 ImportPSYCOPG22 ImportPsycopg2.extras3 4conn = Psycopg2.connect (Database=self.dbname, User=self.username, Password=self.password, Host=self.host, port=self.port)5cursor = Self.conn.cursor (cursor_factory=psycopg2.extras.DictCursor)6sql =""7 cursor.execute (SQL)8rows =Self.cursor.fetchall ()9 #The elements in the rows at this point are the structure of the rowdict type,Ten forRowinchrows: One Printrow['a column name'] AccessReference: Http://yuanjun.me/postgresql/pythoncao-zuo-postgresql#
Pear::D B is the choice of a ADODB database, in addition to the Postgres, this article describes how to use DB to join the database with an example
Installing pear is not covered in this article. In pear, the class that joins the database has the following:
1 "MDB";
2 "MDB2: Because MDB2 's author has been looking forward to PDO into release status, so far MDB2 has been beta version;"
3 "PDO: Connection speed should be the fastest, is a C module, but
Every movie needs a director and every rented movie needs to exist in the store. How does we make sure something in another table exists before inserting new data? This lesson would teach us about foreign keys and references.CREATE TABLEdirectors (ID SERIALPRIMARY KEY, nameVARCHAR( -)UNIQUE not NULL);CREATE TABLEMovies (id SERIALPRIMARY KEY, titleVARCHAR( -) not NULL, release_date date, Count_starsINTEGER, director_idINTEGER REFERENCESdirectors (ID));Now, if we try to insert to movies table som
Tags: lease rect char LTE unique code name error STRLet's say we have a bank. Our bank wants to give each account for each user a unique name, for instance, "Personal" or "Checking." How can we do sure each account have a unique name for each user? ADD UNIQUE constraint when create a new table: CREATE TABLE directors (
PRIMARYKEY,
VARCHAR(UNIQUE notNULL
) Change existing table, modify one field to is unique: ALTER TABLE ADD CONSTRAINT UNIQUE (name) So, if we trying to insert the dupl
Number of records in table: 1578463
Select COUNT (*) from Reorder_guideline; Count---------1578463 (1 Row Records) 2. three statements creating tables CREATE TABLE: (1) most commonly used (23171.485ms) A1stream_db=> CREATE table reorder_guideline_2 as table reorder_guideline; Time: 23171.485 ms (2) with unlogged logo (1734.085ms) Create unlogged table reorder_guideline_2 as table reorder_guideline; Time: 1734.085 ms (3) temporary table with temp ID (1666.934ms) Create temp table reorder_gu
Found an article on the network http://www.linuxidc.com/Linux/2010-04/25232.htm, as follows: Ubuntu 9.10 under PostgreSQL 8. 4 solutions to forgotten passwords Ubuntu9.10 Next PostgreSQL 8. 4 Solutions to forgotten passwords:1. Edit the pg_hba.conf in the83# IPV4 Local connections:$ host All 127.0.0.1/32Trust[email protected]:/etc/postgresql/8.4/main$ sudo vim pg_hba.conf[email protected]:/etc/postgresql/8.4/main$ sudo/etc/init.d/postgresql-8.4restart* restarting PostgreSQL8.4Database Server2. [
Statement:Postgres-version 9.2.5* Specific installation methods refer to the following link:1. http://blog.scimpr.com/2014/08/11/ubuntu12-04%E3%81%A7postgresql%E3%81%AE%E5%85%A8%E6%96%87%E6%A4%9C%E7%B4% a2%e3%80%9ctextsearch_ja/* Summary of problems encountered during installation:1. The "Make use_pgxs=1" Command error occurred when the link operation was performedTip: "Pgxs.mk File not found" error, reason, missing reference rpm package.Execution: Yum Install
process them separately according to the various commands of the client.The client initiates the request, and the PG server initiates a postgres access process for that request, which establishes a connection for that client through access. This postgres access process enters an infinite loop, waits for the client to request and pass the service for it until the process terminates, connecting the fracture.
Label:Recently the company requested to back up the database, so we looked up the comparative information. Don't say much nonsense, into the subject. Objective: To regularly back up the Postgres database under Ubuntu, and to pack and upload to the designated FTP server. After finding the information, the workaround: ① Write a backup database, package compression, upload the specified FTP script. ② adds the script to the Ubuntu scheduled Tasks crontab.
Label:1. Switch to Postgres user;2. Enter: Psql, enter the client psql of PostgreSQL;3.\l View all the current databases;4.psql Database1 connected to database1 this database;5. \dt View all the tables of the currently connected database (DATABASE1);6. \d Table1 View the table structure of table table1;Also: Modify a user's password in ubuntu:1. Switch to the root account;2. passwd account name;3. Follow the instructions, enter a new password, complet
Label:Excerpt from: http://www.cnblogs.com/yjf512/p/4402096.html The view in Postgres scans the sub-table when it is queried, while materialized views actually save the data in a single table. Materialized views are something that is only after 9.3. Create a View CREATE OR REPLACE VIEW student_view asselect *from
student
left JOIN teacher
on= teacher.id; Create a materialized view CREATE VIEW student_view_m asselect *from
stud
1. Save Excel as a CSV2. Open CSV format with TXT3. Encoded in UTF-8 format, save as Blacklist20141231.csv4. Create a tableCreate table backlist_20141231 (date varchar (20), mobile number nvarchar (20), channel nvarchar (50));5. Using the Copy command, copy backlist_20141231 from ' D:/blacklist20141231.csv ' delimiter as ', ' csv quote as ';This error, is not carefully caused, from ' D:/blacklist20141231.cs ' should be from ' d:/blacklist20141231.csv '; change it.6. Now the encoding format or GB
Tags: Linux shell postgresIn the work often to develop and test import and export some test database, so wrote a script for easy operation.The company is currently using the postgres9.3 database.#!/bin/bash #定义一些变量和操作命令 dbs= "DB1NBSP;DB2NBSP;DB3NBSP;DB4" Expdb_cmd=/usr/pgsql-9.3/bin/pg_dump DBCMD=/usr/ Pgsql-9.3/bin/psql dbuser=postgres dbsvr=mydbhost1 #导出数据库 functionexportdb () {read-p " inputdatabaseusernametoexport: "srcdb read-p" inputexportpath:
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