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Questions tagged [serialization]

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Does timestamp protocol following thomas's write rule allow non-view-serializable schedules in some cases?

I have came across following line in text book (Database System Concepts Textbook by Avi Silberschatz, Henry F. Korth, and S. Sudarshan $6e$) page no. 686: Thomas’ write rule allows schedules that ...
2
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1answer
51 views

What is an Intent Lock in SQL Server

I have this query SET TRANSACTION ISOLATION LEVEL SERIALIZABLE BEGIN TRAN UPDATE c SET c.Score = 2147483647 FROM dbo.Comments AS c WHERE c.Id BETWEEN 1 AND 5000; Which have these stats +----------...
9
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2answers
460 views

Does SQL Server's serializable isolation level lock entire table

Me and a colleague of mine discussed the implications of use of the serializable isolation level. He said it locked the entire table, but I disagreed to that telling him it potentially could but it ...
3
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1answer
49 views

PostgreSQL Serialisation failure on different ids

Serializable isolation mode can be used to avoid race conditions when upserting equal ids. So for create table u(uid int primary key, name text); if we run two similar transactions T1 and T2: begin ...
0
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0answers
49 views

PostgreSQL Race condition and Serializable

Hello I try to debug a tricky race condition in my app (golang, pq, sqlx, postgresql Debian 10.6-1.pgdg90+1). I have a table CREATE TABLE j ( id BIGSERIAL PRIMARY KEY NOT NULL, ...
2
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0answers
107 views

What is the meaning of Order preserving Conflict Serializable schedules?

I was going through the concept of order preservation in Conflict Serializable class and I came across Order preserving conflict serializable (OCSR in short). The following is the definition of OCSR ...
1
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0answers
39 views

View serializable schedule

Any view serializable schedule that is not conflict serializable must contain a blind write. (Source: Wikipedia) Why is this statement true? I referred some links like this but am still not able to ...
3
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1answer
353 views

Forced serialization on inline table valued function

Apologies if this is a stupid question. We are attempting to convert our multi-statement table valued functions (MSTVFs) to inline table valued functions (ITVFs), to avoid the forced serialization of ...
1
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2answers
671 views

Are MySQL InnoDB transactions serializable?

I am confused whether or not MySQL transactions are serializable and whether or not read-anomalies are guarded against? For example, what if I SELECT a value from a row, then UPDATE that row by ...
1
vote
1answer
43 views

Serializability schedules: can someone help me understand it?

I am struggling with the Databases courses I have, so I am trying to find answer to my question. This has been asked: Add the appropriate locks to enforce serializability on the following ...
1
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0answers
16 views

Do start and end points change conflict serialisability?

If we have two transactions, and the following schedule: S1 R1(X) S2 R2(X) R2(Y) E1 W2(X) W2(Y) E2 where Si and Ei indicate the start and end of the ith transaction respectively. Does this change ...
0
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1answer
542 views

Storing data in multiple rows vs serialized data

I am currently designing a database table where I store list of courses chosen by students for a session. My current design has to do with storing each course in a row and a student can have up to 30 ...
0
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1answer
427 views

Postgres: turn off formating for xml export?

I want to export some table to xml file: \o output.xml SELECT table_to_xml('modified_records', TRUE, TRUE, ''); However, I'm struggling with psql formatting. The best I managed to get is: \t on \x ...
2
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3answers
5k views

What is meant by a blind write in a schedule?

I know that every conflict-serialisable schedule is view-serialisable but the converse is not true. I read in a webpage that when a schedule is view-serialisable but not conflict-serialisable then ...
1
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1answer
421 views

PostgreSQL visibility of records changes from other transaction inside the current one

I have a table "tst" which has a "status" column using which we process records in that table. Once the records are processed we set the status to 'Y'; #\d tst Table "core.tst" ...
4
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1answer
652 views

Challenges with Key with Gaps?

I had a mistake with a trigger which resulted in errors in PostgreSQL 9.4.3 on x86_64-unknown-linux-gnu, compiled by gcc (Debian 4.9.2-10) 4.9.2, 64-bit. Each time during the error, the primary key ...
4
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1answer
13k views

SELECT in trigger function in two tables

My table and trigger in PostgreSQL 9.4.3 on x86_64-unknown-linux-gnu, compiled by gcc (Debian 4.9.2-10) 4.9.2, 64-bit: CREATE TABLE measurements ( measurement_id SERIAL PRIMARY KEY NOT NULL, ...
6
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1answer
1k views

debugging PostgreSQL serialization failures

I am trying to migrate our PostgreSQL 9.4 database from transaction level READ COMMITTED to either REPEATABLE READ or SERIALIZABLE. In either case, I'm exposed to a new set of errors with the format: ...
2
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1answer
309 views

Does READ COMMITTED always start over after serialization failures while SERIALIZABLE simply fails?

On the PostgreSQL Concurrency With MVCC page, it says: know what you’re thinking though: what about a two transactions updating the same row at the same time? This is where transaction isolation ...
1
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0answers
143 views

Turn off serialization failure logging

Is it possible to turn off serialization failure logging? If so, how? For example, my log is filled with this example: ERROR: could not serialize access due to read/write dependencies among ...
1
vote
1answer
876 views

How to configure read transactions to never cause other write serialization transactions to fail

I am protecting critical transactions with application mutexes and SERIALIZABLE. I presume that this makes these operations as acid as possible, but now I'm concerned that reads might cause failures ...
1
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3answers
4k views

psql: id SERIAL PRIMARY KEY not starting with 1?

This is something I don't understand, can somebody explain? I create a table CREATE TABLE cali (id SERIAL PRIMARY KEY, ALK_from char, ALK_to char, AND_from char, AND_to char); Then ...
35
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5answers
22k views

Locking issue with concurrent DELETE / INSERT in PostgreSQL

This is pretty simple, but I'm baffled by what PG does (v9.0). We start with a simple table: CREATE TABLE test (id INT PRIMARY KEY); and a few rows: INSERT INTO TEST VALUES (1); INSERT INTO TEST ...
5
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2answers
3k views

How do I implement insert-if-not-found for transactions at serializable isolation level?

I'm having a hard time figuring out how to exactly implement a 'insert if not found' function. Consider the following. We have a table called artist with 2 columns, (name, id) where name is the ...
3
votes
1answer
2k views

Send data from SQL to a serial port or IP address

I've been asked to integrate SQL transaction data with a video monitoring system in real-time. The video system's application is only capable of receiving data by listening on a serial port or a ...
2
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1answer
2k views

Data type for protobuf objects in mysql

I would like to store some protobuf objects in a MySQL database. The objects are created in a Java application. The object is accompanied with a textual type identifier and a timestamp. +------------+...