dialnero.blogg.se - Mapping pandas data types to redshift data types

#Mapping pandas data types to redshift data types for free#
#Mapping pandas data types to redshift data types how to#

Only use TIMESTAMPZ when dealing with multiple time zones, good data warehouses use the same timezone across all data.

When you are just dealing with the DATE, i.e the day, month, or year then use DATE.

Try and set a default flag as it will save you in the long run.

Don't use CHAR(1) or VARCHAR(1) when you could use BOOL as CHAR(1) uses up 4 bytes of data and VARCHAR(1) uses 6 bytes when BOOL uses 1 byte.

If you only need two decimal places then just specify 2

When dealing with decimals, be smart about how many decimal points, it helps performance.

INT2 is obviously more performant than INT4/INT8 however it will cap out at 32767 so only use it for small numbers.

INTEGERS don't have decimal places, so don't use them when your customer needs to go down to the decimal level, i.e Currency.

Firstly, numbers are WAY more performant than text so you should never use CHAR or VARCHAR when you could be using INT, DECIMAL, or DATE.

So there's a lot of data types to pick, and plenty of overlap, so why not just use VARCHAR(999) for everything and go about your day? Reasons, that's why! The below will help.

#Mapping pandas data types to redshift data types how to#

Use this for dealing with time across various time zonesīelow are some examples of how to use the above data types in your code.Įnter fullscreen mode Exit fullscreen mode Use this for dealing with time AND where your entire data warehouse is in the same timezone Use this for dealing with time spanning as small as a day, ie.

VARCHAR will always use up at least 6 bytes of data, even if you specify VARCHAR(2) So a in a VARCHAR(100) the word 'Christmas' will only use 9 of that 100, saving space. Unlike CHAR it will only use however much space has been entered.

#Mapping pandas data types to redshift data types for free#

VARCHAR allows for varying character length which is good for free text fields. VARCHAR, CHARACTER VARYING, NVARCHAR, TEXT CHAR will always use up at least 4 bytes of data, even if you specify CHAR(2) Use when your column is always going to be a fixed length. Which can cause issues with EXACT object matching. CHAR always takes up all of the space you specify, so if you specify char(100) but only put 'Hi' into the column, the remain 98 characters of space will be filled with spaces. You can specify that the default value is true or false, if you don't specify a default value then the default value will be nullĬHAR is a fixed length text string, ignore references to NCHAR and BPCHAR those are old functionality merged all into one.

It can also get represented as a checkbox. For example decimal(10,2) means ten numbers max with two decimal places, this equates to 8 digits on the left of the decimal, and 2 on the right.įor storing smaller, rounded down, floating point numbersįor storing larger, non rounded, floating point numbersīoolean is a single byte flag which is either 1 or 0, true or false. When you classify a column as decimal you must declare both the TOTAL length and then how many decimals. This is for WHOLE numbers that only take up 2 bytes of data, range: -32768 to +32767Īlso for whole numbers that only take up 4 bytes of date, range: -2147483648 to +2147483647Īlso for whole numbers that only take up 8 bytes of date, range: -9223372036854775808 to 9223372036854775807įor numbers with decimal points, up to 38 digits total.