Abstract: A technique includes determining a statistic for values associated with at least one column of a database based at least in part on a first sample of the values; and determining a degree of change in a second sample of the values relative to the first sample; and estimating a count of unique values for the column(s). The estimation of the count of unique values includes selectively incrementally updating the statistic using the second sample based at least in part on the determined degree of change; and basing estimation of the count at least in part on the updated statistic. The technique further includes processing a query to the database based at least in part on the count.

Abstract: A method of managing a database including creating an initial counting bloom filter (CBF) instance having an array of counters and hash functions that map an inserted value to the array of counters, and designating the initial CBF instance as a current CBF instance, and sequentially inserting each value of a sample data set of a table column into the hash functions of the current CBF instance and incrementing counters of the array of counters to which the value is mapped. The method further includes, prior to inserting each value into the hash functions of the current CBF instance, when a number of counters of the array of counters having non-zero values is at least at a threshold level, designating the current CBF instance as an old CBF instance, creating a new CBF instance having an array of counters and hash functions that map an inserted value to the array counters, and designating the new CBF instance as the current CBF instance.

Abstract: Incrementally updating statistics includes sampling rows from a database column in a database to generate a first sample, sampling a subset of modified rows from the database column after generating the first sample to generate a second sample, determining whether distribution changes occurred to the database column based on the first and second samples, and updating a database statistic about the database column in response to determining that a distribution change exists.

Abstract: A technique includes determining a statistic for values associated with at least one column of a database based at least in part on a first sample of the values; and determining a degree of change in a second sample of the values relative to the first sample; and estimating a count of unique values for the column(s). The estimation of the count of unique values includes selectively incrementally updating the statistic using the second sample based at least in part on the determined degree of change; and basing estimation of the count at least in part on the updated statistic. The technique further includes processing a query to the database based at least in part on the count.

Abstract: In one example in accordance with the present disclosure, a method for determining query plans includes obtaining a current query and generating a first literal and a first signature key from the current query. The method includes determining that the first signature key matches a second signature key stored in a parser cache and obtaining a literals data structure corresponding to the second signature key. The literals data structure comprises a group of literals, a list of high and low boundary intervals and a parameterization indicator. The method includes identifying, using the parameterization indicator, a parameterized literal in the group of literals. The method includes determining that a high and low boundary interval for the second parameterized literal contains the first literal and executing a stored query plan on the current query.

Abstract: Query plan post optimization analysis and reoptimization can include analyzing query plans input from a query plan optimizer, identifying a suboptimal query plan among the input query plans, and applying corrective actions to reoptimize the identified suboptimal query plan before execution.

Abstract: In one example in accordance with the present disclosure, a method for determining query plans includes obtaining a current query and generating a first literal and a first signature key from the current query. The method includes determining that the first signature key matches a second signature key stored in a parser cache and obtaining a literals data structure corresponding to the second signature key. The literals data structure comprises a group of literals, a list of high and low boundary intervals and a parameterization indicator. The method includes identifying, using the parameterization indicator, a parameterized literal in the group of literals. The method includes determining that a high and low boundary interval for the second parameterized literal contains the first literal and executing a stored query plan on the current query.

Abstract: A method of managing a database including creating an initial counting bloom filter (CBF) instance having an array of counters and hash functions that map an inserted value to the array of counters, and designating the initial CBF instance as a current CBF instance, and sequentially inserting each value of a sample data set of a table column into the hash functions of the current CBF instance and incrementing counters of the array of counters to which the value is mapped. The method further includes, prior to inserting each value into the hash functions of the current CBF instance, when a number of counters of the array of counters having non-zero values is at least at a threshold level, designating the current CBF instance as an old CBF instance, creating a new CBF instance having an array of counters and hash functions that map an inserted value to the array counters, and designating the new CBF instance as the current CBF instance.

Abstract: A method of estimating a number of unique entry counts of an attribute in a database comprises, with a processor: identifying a sample of entries from an attribute database, determining frequencies of a number of input observations of the sample of entries, determining a number of high frequency values of the sample of entries, and estimating a number of unique entry counts of an attribute within the attribute database using a counting Bloom filter and based on the frequencies of the input observations and the high frequency values.

Abstract: A method and apparatus are disclosed for searching for a radar signal within signals received by a wireless device. The wireless device may receive signals within a first frequency segment and a second frequency segment, which is adjacent to the first frequency segment. The wireless device may search for the radar signal within the first frequency segment or the second frequency segment based, at least in part, on Fast Fourier Transform bins associated with the received signals.

Abstract: A method for creating a joined data set from a join input data set is disclosed. The method starts by categorizing the join input data set into a high-skew data set and a low-skew data set. The low-skew data set is distributed to the plurality of CPUs using a first distribution method. The high-skew data set is distributed to the plurality of CPUs using a second distribution method. The plurality of CPUs process the high-skew data set and the low-skew data set to create the joined data set.

Abstract: Incrementally updating statistics includes sampling rows from a database column in a database to generate a first sample, sampling a subset of modified rows from the database column after generating the first sample to generate a second sample, determining whether distribution changes occurred to the database column based on the first and second samples, and updating a database statistic about the database column in response to determining that a distribution change exists.

Abstract: A method and apparatus for improving the accuracy of a round trip time (RTT) estimate between a first device and a second device are disclosed. The method involves calculating an acknowledgement correction factor and a unicast correction factor. These correction factors are used to compensate for symbol boundary time errors resulting from multipath effects.

Abstract: A method and apparatus for improving the accuracy of a round trip time (RTT) estimate between a first device and a second device are disclosed. The method involves calculating an acknowledgement correction factor and a unicast correction factor. These correction factors are used to compensate for symbol boundary time errors resulting from multipath effects.

Abstract: There is provided a computer-executable method of executing an outer join on a parallel database management system. An exemplary method comprises receiving an outer skewed values list (SVL). The outer SVL may comprise values that are indicated to be skewed. The exemplary method further comprises receiving an inner SVL. The inner SVL may comprise values that are indicated to be skewed. Additionally, the exemplary method comprises partitioning the outer table and the inner table across a plurality of join instances, based on the outer SVL and the inner SVL. A missing skew value is identified. The missing skewed value may be a value of the inner SVL that is not found in the inner table. The outer join is performed using the plurality of join instances, based on the missing skewed value.

Abstract: A method for creating a joined data set from a join input data set is disclosed. The method starts by categorizing the join input data set into a high-skew data set and a low-skew data set. The low-skew data set is distributed to the plurality of CPUs using a first distribution method. The high-skew data set is distributed to the plurality of CPUs using a second distribution method. The plurality of CPUs process the high-skew data set and the low-skew data set to create the joined data set.

Abstract: A method and apparatus for improving the accuracy of a round trip time (RTT) estimate between a first device and a second device are disclosed. The method involves calculating an acknowledgement correction factor and a unicast correction factor. These correction factors are used to compensate for symbol boundary time errors resulting from multipath effects.

Abstract: A method of estimating a number of unique entry counts of an attribute in a database comprises, with a processor: identifying a sample of entries from an attribute database, determining frequencies of a number of input observations of the sample of entries, determining a number of high frequency values of the sample of entries, and estimating a number of unique entry counts of an attribute within the attribute database using a counting Bloom filter and based on the frequencies of the input observations and the high frequency values.

Abstract: A method of providing synchronization-free station locating in a wireless network is provided. In this method, an AP having a known location sends a unicast packet to the station and notes its time of departure TOD(D). The station receives the unicast packet, notes its time of arrival TOA(D), sends an acknowledgement packet to the AP, and notes its time of departure TOD(D_ACK). The AP receives the acknowledgment packet and notes its time of arrival TOA(D_ACK). Notably, a distance between the AP and the station can be accurately determined using a first difference between the TOA(D_ACK) and the TOD(D) and a second difference between the TOD(D_ACK) and the TOA(D). A plurality of such computed distances between a plurality of APs and the station can be used to determine an accurate location of the station.