Basic information

Skip this section if you want details specific to a particular database table.

Location of this database file

This database file/files is/are specific to Cumulus MX (as the file name suggests), not used by legacy Cumulus 1
For MX Releases 3.0.0 to 3.11.4 inclusive, there were two databases with this name:
1. One database table with this name was held in Random Access Memory for MX Releases 3.0.0 to 3.11.4 inclusive
2. One database table with this name is stored as CumulusMX/data/cumulusmx.db (get case of each character correct unless Microsoft Windows Operating System)
The two database tables were merged from release 3.12.0 (beta build 3134) and stored as /CumulusMX/data/cumulusmx.db (get case of each character correct unless Microsoft Windows Operating System)

Database type

This file/files holds a SQLite3 database. Databases of this type are based on sequential file design, i.e. each row in the database table is sequenced by when created (new rows are only appended on end), and given a sequential number to act as primary key (numbers are not automatically revised when a row is deleted).

The MX Weather Diary also uses a SQLite3 database stored in CumulusMX/data/diary.db.

Reading/editing database table outside MX

There are many software tools available that can read/edit SQLite3, should you wish to examine this database.

You could use any application that can read ODBC files (e.g. Libre Office's Base functionality), these can read the MX databases.

You might find sqlitebrowser easiest to use in a Linux environment.

You might try phpLiteAdmin if your device runs a Microsoft Windows Operating System.

Database Tables included

The following table lists the tables found in this database, indicating which release added the table, and where further details can be found.

Table name	How MX updates	Introduced	Description	Editor within MX	Further details
RecentData	Updated once a minute when MX is running	MX beta 3.0.0 Database of this name with this table originally in RAM In 3.12.0 (beta build 3134) table moved to external file	The update.txt for CumulusMX at release 3.12.0 (beta build 3134) states "Change: Cumulus MX now uses a persistent database to store the recent 1 minute data - This means that charts, recent web tags, and internal calculations for trends and periodic values will be more accurate after a restart - If Cumulus MX is offline for a prolonged period, data for that offline period will obviously still be at the station logging interval resolution".	No editor for Cumulus user	Recent history and #RecentData table
SqlCache	Updated when certain conditions are met and SQL is queued	MX 3.21.0	The update.txt for CumulusMX at release 3.21.0 states "New - Failed MySQL commands can now be individually edited/deleted Changed - Failed MySQL commands are now stored in the SQLite database to persist across Cumulus runs"	Edit or purge the failed MySQL command queue using Utils menu -->> PurgeMySQL	MySqlConnect and #SqlCache table
StandardData	At time of writing, the current MX release does not use this table	MX beta 3.0.0 (always in file)	In this forum post Steve Loft describes this table as being for a possible future enhancement. It is believed this is the table that Steve had developed in Cumulus 2, as a replacement for the Monthly_log_files.	At time of writing, the current MX release does not use this table	#StandardData table
sqlite_sequence	Developer has not stated when updated	MX 3.21.0	Developer has not supplied a description	Not known	#sqlite_sequence table

RecentData table

This table has the following columns:

Column number #	Column name	Column type	Properties	Description	Example column value
0	Timestamp	datetime	Primary Key, can never be NULL, No Default Value,	Dates and times for the last 7 days, at whatever interval available (at logging interval for historic archive data, at one minute intervals while MX is running)	2021-07-31 19:44:00
1	WindSpeed	float	Not NULL, No Default Value	The average wind speed (see Wind_measurement#Weather_Stations_and_Cumulus for links) calculated at the stated time, if necessary converted to units requested	2.2593056529
2	WindGust	float	Not NULL, No Default Value	The spot gust speed recorded at the stated time, if necessary converted to units requested	6.99691241605804
3	WindLatest	float	Not NULL, No Default Value	The spot latest wind speed recorded at the stated time, if necessary converted to units requested	3.15989597323001
4	WindDir	integer	Not NULL, No Default Value	The wind bearing (0 =calm), (1 to 360 = number of degrees)	315
5	WindAvgDir	integer	Not NULL, No Default Value	The average wind bearing over the defined period	270
6	OutsideTemp	float	Not NULL, No Default Value	The measured outside air temperature, if necessary converted to units requested	17.0
7	WindChill	float	Not NULL, No Default Value	The wind chill, either calculated by MX, or supplied by weather station. (Note: strictly only valid for low temperatures and significant wind speeds)	(In the example used here, temperature in previous column was too high for wind chill, so the value was set to agree with 'OutsideTemp' column instead)
8	DewPoint	float	Not NULL, No Default Value	The dew point, either calculated by MX, or supplied by weather station, for the stated time.	11.9134549845367
9	HeatIndex	float	Not NULL, No Default Value	The USA Heat index as calculated by Cumulus for the stated time (if the temperature is high enough)	(In the example used here, temperature in 'OutsideTemp' column was too low for heat index, so the value was set to agree with 'OutsideTemp' column instead)
10	Humidity	float (1 decimal place)	Not NULL, No Default Value	The Relative Humidity reported by the station at the stated time	72.0
11	Pressure	float	Not NULL, No Default Value	The sea level pressure at the stated time, either as reported by the station or calculated by Cumulus from the absolute pressure reported by the station, if necessary converted to units requested	996.400024414062
12	RainToday	float	Not NULL, No Default Value	The rainfall for today so far, calculated by Cumulus from the rain counter (column 15) now minus the rain counter at start of day, if necessary converted to units requested	4.5
13	SolarRad	integer	Not NULL, No Default Value	Solar radiation value reported by station at stated time	200
14	UV	float	Not NULL, No Default Value	The Ultra Violet Index reported by station at stated time	3.0
15	raincounter	float	Not NULL, No Default Value	The rain counter is used by Cumulus for all rainfall outputs, this is its value at stated time	550.4
16	FeelsLike	float	Not NULL, No Default Value	The Feels Like temperature calculated by MX at stated time	17.0782773978147
17	Humidex	float	Not NULL, No Default Value	The Canadian Humidity Index, calculated by Cumulus at the stated time	19.1775362738161
18	AppTemp	float	Not NULL, No Default Value	The Apparent temperature, calculated by MX at the stated time	16.8864476063546
19	IndoorTemp	float	Not NULL, No Default Value	The indoor temperature directly as reported by station at stated time	120.89999961853
20	IndoorHumidity	integer (0 decimal places, contrast with column 10)	Not NULL, No Default Value	The indoor relative humidity directly as reported by station at stated time	61
21	SolarMax	integer	Not NULL, No Default Value	The calculated maximum value for solar radiation at stated time	1026
22	Pm2p5	float	Not NULL, No Default Value	Air Quality expressed in terms of particulate matter of 2.5 μm, or less, (?? Rolling 24 hours average ??)	1.5
23	Pm10	float	Not NULL, No Default Value	Air Quality expressed in terms of particulate matter of 10 μm, or less, (?? Rolling 24 hours average ??)	1.7
24	RainRate	float	Not NULL, No Default Value	The rainfall rate calculated for the stated time	303.2

See Recent history page for more details.

SqlCache table

There is a MX setting (Settings -->> MySQL settings -->> General Options -->> Buffer commands on failure) that when enabled allows failed commands to be stored here.

This table holds a list of MySQL commands that are in the queue for MySqlConnect to run again.

Commands that fail because the database server is down are added to the queue when the setting is enabled (although MX will not save more than one query referencing same primary key). Because the error returned by the server cannot be predetermined, MX instead checks the error returned is not one of the following reasons before adding it to queue:

ParseError (the query does not make sense)
EmptyQuery (query has not been specified)
TooBigSelect (there is a limit to how much data can be selected)
InvalidUseOfNull (the schema has to say for each column whether null is permitted)
MixOfGroupFunctionAndFields (syntax can't mix these)
SyntaxError (an error in the SQL syntax)
TooLongString (there is a limit to what can be input)
WrongColumnName (the column name must exist in the referenced table/view)
DuplicateUnique (you can't insert a new row with same primary key as an existing row)
PrimaryCannotHaveNull (the primary key must be set to a specific value)
DivisionByZero (certain mathematical operations cannot be handled)

Here is the relevant create table instruction, so this tells you the 2 fields in the table as Mark Crossley created it:

CREATE TABLE "SqlCache"( "key" integer primary key autoincrement not null, "statement" varchar)

The table contents are simple to explain, each time a new command is stored it is assigned a new number (that is automatically incremented from last number used) and the command itself is stored in a variable text length entry.

StandardData table

At time of writing this documentation, the latest MX release does not use this table, and it has zero rows. A forum post by Steve Loft about a database based logging proposal for Cumulus 3 (MX) confirms the original purpose was to improve the ability to Correct Extremes Records by storing the most frequent and accurate extremes possible.

While that does not specifically explain this table, his choice of table name suggests he was planning to either replace, or duplicate, the use of text files for logging data. It appears he was actually thinking about implementing Monthly_log_files#Enhancement never implemented from his inclusion of "Lo" and "Hi" values in the column list.

The only alternative theory is Steve Loft actually thought he could improve on the Recent history functionality, by storing the highest and lowest readings read from weather station in-between the one minute resolution.

Here is the relevant create table instruction, so this tells you the 17 fields in the table as Steve created it (these have never been changed):

CREATE TABLE "StandardData"( "Timestamp" datetime primary key not null , "Interval" integer , "OutTemp" float , "LoOutTemp" float , "HiOutTemp" float , "DewPoint" float , "LoDewPoint" float , "HiDewPoint" float , "WindChill" float , "LoWindChill" float , "HiWindChill" float , "InTemp" float , "LoInTemp" float , "HiInTemp" float , "Pressure" float , "LoPressure" float , "HiPressure" float )

sqlite_sequence table