Optimizing database table scans in the presence of ordered data

A computer system for optimizing database table scans in a presence of a set of Summarizing Meta-Data Object (SMDO) records that store a maximum value, a minimum value, and a Bloom filter associated with each respective span of rows in a table for a column and that store computed values for cumulative maximum, cumulative minimum, and cumulative Bloom filter for the column over all previously generated spans of rows in the table, the computer system comprising:

• a bus system;
• a storage device connected to the bus system, wherein the storage device stores program instructions;
• and
• a processor connected to the bus system, wherein the processor executes the program instructions to:
• read an SMDO record in the set of SMDO records corresponding to a most recent span of rows for a column in the table associated with a query predicate, wherein the SMDO record includes SMDO fields required by a type of the query predicate;
• (i) determine whether a condition for excluding a span of rows is true for the SMDO record corresponding to the most recent span of rows for the column based on the type of the query predicate;
• (ii) add the most recent span of rows to a list of spans of rows to scan for results of the query predicate in response to determining that a condition for excluding a span of rows is not true for the SMDO record corresponding to the most recent span of rows for the column based on the type of the query predicate;
• (iii) determine whether a condition for excluding all preceding spans of rows is true for the SMDO record corresponding to the most recent span of rows for the column based on the type of the query predicate;
• (iv) stop reading the set of SMDO records in response to determining that a condition for excluding all preceding spans of rows is true for the SMDO record corresponding to the most recent span of rows for the column based on the type of the query predicate;
• and
• (v) read another SMDO record in the set of SMDO records corresponding to a next most recent span of rows for the column in the table associated with the query predicate and repeat steps (i)-(v) with the another SMDO record being used as the SMDO record recited in steps (i)-(v) in response to determining that a condition for excluding all preceding spans of rows is not true for the SMDO record corresponding to the most recent span of rows for the column based on the type of the query predicate.

A computer program product for optimizing database table scans in a presence of a set of Summarizing Meta-Data Object (SMDO) records that store a maximum value, a minimum value, and a Bloom filter associated with each respective span of rows in a table for a column and that store computed values for cumulative maximum, cumulative minimum, and cumulative Bloom filter for the column over all previously generated spans of rows in the table, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a computer to cause the computer to perform a method comprising:

• reading, by the computer, an SMDO record in the set of SMDO records corresponding to a most recent span of rows for a column in the table associated with a query predicate, wherein the SMDO record includes SMDO fields required by a type of the query predicate;
• (i) determining, by the computer, whether a condition for excluding a span of rows is true for the SMDO record corresponding to the most recent span of rows for the column based on the type of the query predicate;
• (ii) responsive to the computer determining that a condition for excluding a span of rows is not true for the SMDO record corresponding to the most recent span of rows for the column based on the type of the query predicate, adding, by the computer, the most recent span of rows to a list of spans of rows to scan for results of the query predicate;
• (iii) determining, by the computer, whether a condition for excluding all preceding spans of rows is true for the SMDO record corresponding to the most recent span of rows for the column based on the type of the query predicate;
• (iv) responsive to the computer determining that a condition for excluding all preceding spans of rows is true for the SMDO record corresponding to the most recent span of rows for the column based on the type of the query predicate, stopping, by the computer, reading the set of SMDO records;
• and
• (v) responsive to the computer determining that a condition for excluding all preceding spans of rows is not true for the SMDO record corresponding to the most recent span of rows for the column based on the type of the query predicate, reading, by the computer, another SMDO record in the set of SMDO records corresponding to a next most recent span of rows for the column in the table associated with the query predicate and repeating steps (i)-(v) with the another SMDO record being used as the SMDO record recited in steps (i)-(v).