Put some data into the same tablet in a specified manner

General
1

Hi
Excuse me.
If I use the hash sharding method and specify the id as the primary key，as shown in the following example:
CREATE TABLE tracking (id int PRIMARY KEY)

What method can I use to place records with ids such as 10,11,12,13 in the same tablet ?
Can I use split into? For example:
CREATE TABLE tracking (id int PRIMARY KEY) split into 1 tablet

Thanks.

2

Hi @ZhenNan2016 You can split tablets using range sharding to place records into the same tablet.

For example:

CREATE TABLE tracking (id INT, PRIMARY KEY (id asc)) SPLIT AT ((100));

The above will cause the table to be split at the given value and will let you insert all your specified values in the same tablet.

1 Like
3

Reference:

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4

Hi @vaibhav_yb

Yes, it’s a good idea.
However, I hope that the processing method of hash sharding also supports placing specified data in the same table tablet.
Do you have any good suggestions?
Thanks.

5

@ZhenNan2016

The only way to guarantee is by having a table like below and making sure they have the same partition_key column value:

CREATE TABLE sample(partition_key int, id int, PRIMARY KEY (partition_key, id));
6

@ZhenNan2016

Why is the requirement for both rows being in the same tablet?

7

Hi @dorian_yugabyte
Excuse me.
I can’t follow you, sorry.
Are k1 and k2 two column fields?
Is the partition_key a combination of k1 and k2 ?
Is this id field a normal column?
Is this the correct table creation statement as follow ?
CREATE TABLE（k1 int，k2 int，id int，PRIMARY KEY(k1，k2));

8

@dorian_yugabyte
Because it is necessary to test some operations on two records in the same tablet, including deadlock testing

9

@ZhenNan2016

I edited the query above, please check again.

Only partition_key column is used for partitioning.

1 Like
10

I got it now.
Thanks.

11

Hi @dorian_yugabyte
I’m sorry to trouble you.
The data is written to the data table according to the algorithm corresponding to hash-sharing.
What tools do we have to quickly calculate the hash value of the partition_key?
I want to see how a data record calculates the hash value of the partition_key and writes it to which tablet.
Thank you very much.

12

See yb_hash_code yb_hash_code() function [YSQL] | YugabyteDB Docs

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13

You can also use table partitioning that is inherited from PostgreSQL: Table partitioning | YugabyteDB Docs

1 Like
14

OK，I got it now.
Thank you very much.