Subject | get values for a certain timestamp |
---|---|

Author | Josef Gschwendtner |

Post date | 2006-07-07T19:14:47Z |

Dear Firebird users,

does anybody have an idea how to solve the following problem in a clever

fashion?

Our Situation:

==============

We have a database with to tables (amongst others).

In table1 (MDP) are several thousand "machine-datapoints" (e.g

machine-speed or temperature)

For each of these datapoints we get data (values) (e.g. 5 m/s) which is

stored in table2 (MD).

Some datapoints are sending a value each second, some only once a day.

Therefore table MD has many million records. Each record has a foreign

key MDP, the value and the timestamp when the value has been measured.

On the timestamp-field in MD is an ascending index.

Our problem:

============

We need to view the (active) values/states of all datapoints at a

certain time, which is given by the user.

Therefore the challenge is, to find out (as fast as possible) the last

stored value/state of each datapoint before the given timestamp.

Thank you for sharing your knowledge.

Josef Gschwendtner

does anybody have an idea how to solve the following problem in a clever

fashion?

Our Situation:

==============

We have a database with to tables (amongst others).

In table1 (MDP) are several thousand "machine-datapoints" (e.g

machine-speed or temperature)

For each of these datapoints we get data (values) (e.g. 5 m/s) which is

stored in table2 (MD).

Some datapoints are sending a value each second, some only once a day.

Therefore table MD has many million records. Each record has a foreign

key MDP, the value and the timestamp when the value has been measured.

On the timestamp-field in MD is an ascending index.

Our problem:

============

We need to view the (active) values/states of all datapoints at a

certain time, which is given by the user.

Therefore the challenge is, to find out (as fast as possible) the last

stored value/state of each datapoint before the given timestamp.

Thank you for sharing your knowledge.

Josef Gschwendtner