Tags: space based build empty query other release cat shared lockVacuum commands exist in two forms, vacuum and vacuum full, and the difference between them is shown in the following table:
No vacuum
VACUUM
VACUUM full
After de
PostgreSQL vacuum Principle 1 Functions and Parameters
From the previous article "PostgreSQL MVCC source code implementation []", we know that PG does not store the old version of undo like Oracle, but directly stores the old version in the relation file. The problem is that there are too many dead tuple files, resulting in increasing relation files and space expansion. To solve this problem, PG introduced the vac
The Design and Application of Vacuum suction cups are briefly described:
Theoretical suction F (n) = effective adsorption area (m2) * vacuum degree (kPa)
If the pressure of compressed air is 5MPa MPa, the vacuum generator can generate a vacuum degree greater than 80 kPa. Generally, 70kpa is used for calculation in Engi
Clothing Vacuum Bags Let us experience its benefits, although the application is not particularly extensive, Changchun fertilizer bag But at least it has been applied to our lives, think of the future will certainly play a greater role in our lives, after the vacuum packaging bags can also be used to install clothes, but do not know AH. Believe in the future, it will use every aspect of the industry. This k
Update: Heikki ' s slides is here!Heikki Linnakangas gave a presentation this past Sunday at FOSDEM on the improved Free Space map (FSM), which tracks UN Used space inside the database, and new visibility map, a bitmap which would indicate which data pages can be skipped Durin G A partial VACUUM. This performance enhancement would affect all users of the upcoming 8.4 software release. You can see that the new FSM implementation looked like back in Oct
The vacuum command is an extended function of SQLite. It imitates the same commands in PostgreSQL. If VACUUM is called with a table name or index name, the table or index will be sorted. In SQLite 1.0, the VACUUM command calls gdbm_reorganize () to sort back-end database files.
GDBM backend is removed from SQLITE 2.0.0, and
application range and industry of vacuum suction cupsVacuum Suction cup, also known as Sucker, is one of the vacuum equipment actuators. The layout is more brief, the installation is more convenient, the appearance is beautiful, the suction holding force is strong and so on characteristic. classification of Vacuum suction cups:1, according to the shape classifica
Vacuum full locks the table and is very inefficient. In practice, vacuum cannot be used to narrow down the pg_class, resulting in a long downtime.In fact, the simplest way to implement vacuum full is to copy a table again, create table B as select * from a; then use table B instead of table.Since pg_class is the basis of all tables, we cannot replace it even if w
Use drones or vacuum cleaners to black out enterprise wireless printers
A drone and a smartphone can intercept data transmitted by wireless printers outside the office building, as demonstrated by a group of iTrust researchers. In addition, the use of a vacuum in the building and a smart phone can also attack enterprise wireless printers.
Use drones to attack wireless printers
Recently, I wrote a blog at
Label:Delete all data from the table:DELETE from [Name]When a large amount of data has been deleted in SQLite, the size of the database file remains the same. The reason: After deleting data from SQLite, unused disk space is added to an intrinsic "free list" to store the data you insert next. Disk space is not lost. However, it does not return disk space to the operating system.There are two ways to solve the problem:1, after the data is deleted, manually execute the SQL "
Tags: top span doc Library MOS module CTI Connect documentationthere is a bug in Python 3.6.0 's Sqlite3 module(see Issue 29003), and the vacuum statement cannot be executed. An exception occurs on execution: Traceback (most recent):File "D:\desktop\cannot_vacuum.py", line, in Conn.execute (' VACUUM ')Sqlite3. Operationalerror:cannot VACUUM from within a transact
World-famous writer and great thinker Spencer. Johnson once said that "the only constant is the change itself", this famous quote is the current Internet era of the real portrayal of the industry. The Tuyere is a succession of changes, unicorn faces are also changing, even the original high stars are also under the impact of the internet to "go down the altar."The stars have "fallen" into the liveFor a long time, fans can only rely on TV, portal or micro-blog words and pictures to pay attention
2down vote
According to documentation
VACUUM reclaims storage occupied by dead tuples.
But according to this post
Dead rows is deleted rows that would later be reused for new rows from inserts or UPDATEs. Some dead Rows (or reserved free space) can is particularly useful for hot (heap-only tuples) updates that can reuse space In the same data page efficiently
PostgreSQL
I. Features of non-inner tires
Inner tire is often referred to as "Low Pressure tire" and "vacuum tire", which can be divided into radial tire and oblique line tire. Non-inner tire has high elasticity and wear resistance, and has good adhesion and heat dissipation performance. In particular, because the tire crown angle is zero, the amount of changes is small when the vehicle advances at high speed, and can maintain good driving stability and smalle
According to a recent observation by the vacuum coating materials network, there are roughly three types of online platforms for steel trading. Here they are simply defined as selling dog meat, self-serving, and expanding business.Dog-meat type. People in the iron and steel industry may often go to some iron and steel information websites to check the current situation and news of the iron and steel industry. However, in recent years, I wonder if you
on the World Wide Web. you can also do a good line in negotiations with suppliers. discount Hermes handbags ukyou can buy outdoor beanbags, if you plan to use them outside the house. you do not have to worry about damages, since they are resistant to different weather conditions. instead of using a regular hammock, you can leave this as another. when you want to control the children playing in the garden, or wait, barbecue is cooking, now you have something else to relax. who will find it easy
.
Fat guys look cool.
In the evening, I finally arrived at longsheng!
7
Month 23
Day
, Sunny, longsheng-Sanjiang, 64 km
, 34
RMB On the road, I saw a bad road, a lot of gray. Fortunately, there was a turban, or it would be terrible. The road surface is very bad. When we say we are building a road, we don't see a road mechanic. when the car is driving, the dust is like fog, and no one can see it. We leave at half past nine a.m. and arrive at a.m, take a break for an hour
, the overcapacity in the steel industry is behind the "flourishing" of steel enterprises ".Where did the extra steel companies come from?According to a small research, since the emergence of the steel industry in the past few years, more and more non-governmental enterprises have joined this bus, which has already been filled with members. Private steel enterprises were also profitable in the early days, and brought about many social employment opportunities. However, the increasing number of p
Looking at the success of more and more steel enterprises, it shows that some steel enterprises are about to leave the winter, but in contrast, there are still many companies with losses. However, with a successful case, we can set an example for learning. According to the observation of vacuum coating materials network, the role of steel enterprises is to develop high-performance steel products.Under the guidance of some large iron and steel enterpri
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