Re: [HACKERS] two dimensional statistics in Postgres

2014-11-08 Thread Tomas Vondra
On 8.11.2014 15:40, Katharina Büchse wrote: I'm sorry if I repeated myself too often, I somehow started answering at the end of your mail and then went up... I promise to do this better next time. Nah, no problem. Better say something twice than not at all ;-) However, I see you've responded

Re: [HACKERS] two dimensional statistics in Postgres

2014-11-07 Thread Katharina Büchse
Ahoj ;-) On 06.11.2014 11:56, Tomas Vondra wrote: Hi, Dne 6 Listopad 2014, 11:15, Katharina Büchse napsal(a): Hi, I'm a phd-student at the university of Jena, Thüringen, Germany, in the field of data bases, more accurate query optimization. I want to implement a system in PostgreSQL that

Re: [HACKERS] two dimensional statistics in Postgres

2014-11-07 Thread Tomas Vondra
On 7.11.2014 13:19, Katharina Büchse wrote: On 06.11.2014 11:56, Tomas Vondra wrote: Dne 6 Listopad 2014, 11:15, Katharina Büchse napsal(a): because correlations might occur only in parts of the data. In this case a histogram based on a sample of the whole table might not get the point and

Re: [HACKERS] two dimensional statistics in Postgres

2014-11-06 Thread Gavin Flower
On 06/11/14 23:15, Katharina Büchse wrote: Hi, I'm a phd-student at the university of Jena, Thüringen, Germany, in the field of data bases, more accurate query optimization. I want to implement a system in PostgreSQL that detects column correlations and creates statistical data about

Re: [HACKERS] two dimensional statistics in Postgres

2014-11-06 Thread Tomas Vondra
Hi, Dne 6 Listopad 2014, 11:15, Katharina Büchse napsal(a): Hi, I'm a phd-student at the university of Jena, Thüringen, Germany, in the field of data bases, more accurate query optimization. I want to implement a system in PostgreSQL that detects column correlations and creates statistical

Re: [HACKERS] two dimensional statistics in Postgres

2014-11-06 Thread Tomas Vondra
Dne 6 Listopad 2014, 11:50, Gavin Flower napsal(a): Could you store a 2 dimensional histogram in a one dimensional array: A[z] = value, where z = col * rowSize + row (zero starting index)? How would that work for columns with different data types? Tomas -- Sent via pgsql-hackers mailing

Re: [HACKERS] two dimensional statistics in Postgres

2014-11-06 Thread Gavin Flower
On 06/11/14 23:57, Tomas Vondra wrote: Dne 6 Listopad 2014, 11:50, Gavin Flower napsal(a): Could you store a 2 dimensional histogram in a one dimensional array: A[z] = value, where z = col * rowSize + row (zero starting index)? How would that work for columns with different data types? Tomas

Re: [HACKERS] two dimensional statistics in Postgres

2014-11-06 Thread Tomas Vondra
Dne 6 Listopad 2014, 12:05, Gavin Flower napsal(a): On 06/11/14 23:57, Tomas Vondra wrote: Dne 6 Listopad 2014, 11:50, Gavin Flower napsal(a): Could you store a 2 dimensional histogram in a one dimensional array: A[z] = value, where z = col * rowSize + row (zero starting index)? How would