Abstract: A drive pulley (12) is formed by a piston-cylinder mechanism in which a seal ring (15) is set on an outer periphery of a fixed piston plate (16) that is in sliding contact with a cylinder inner peripheral surface (12d) of a cylinder (12b), and is driven by being supplied with hydraulic pressure. As a control parameter of a surface roughness shape of the cylinder inner peripheral surface (12d) of the drive pulley (12), a kurtosis (Rku) of a roughness curve and a skewness (Rsk) of the roughness curve, each of which is a height direction characteristic average parameter, are used. The cylinder inner peripheral surface (12d) is set to a surface having a surface roughness shape whose measurement values of the kurtosis (Rku) and the skewness (Rsk) are predetermined respective control values or less. With this, it is possible to surely suppress sliding abrasion of the liquid-tight seal member.

Abstract: A vehicle continuously transmission mechanism includes a seal mechanism to seal a hydraulic chamber defined by fixed and movable members on a back surface side of a movable sheave of a pulley or seal an oil passage communicating with the hydraulic chamber. This seal mechanism has an annular seal member normally brought into intimate contact with an opposing surface of the sliding contact part and a lip seal member formed with an annular lip such that a tip end of the annular lip is directed toward the outside and a side surface of the annular lip located closer to the hydraulic chamber or oil passage is brought into elastic contact with the opposing surface of the sliding contact part.

Abstract: A vehicle continuously transmission mechanism includes a seal mechanism to seal a hydraulic chamber defined by fixed and movable members on a back surface side of a movable sheave of a pulley or seal an oil passage communicating with the hydraulic chamber. This seal mechanism has an annular seal member normally brought into intimate contact with an opposing surface of the sliding contact part and a lip seal member formed with an annular lip such that a tip end of the annular lip is directed toward the outside and a side surface of the annular lip located closer to the hydraulic chamber or oil passage is brought into elastic contact with the opposing surface of the sliding contact part.

Abstract: A belt-drive continuously variable transmission including a lock mechanism for locking a primary moveable sheave of a primary pulley in a highest transmission ratio position. The lock mechanism includes a fixed side axial groove extending on an outer circumferential surface of a primary fixed sheave shaft, a moveable side axial groove extending on an inner circumferential surface of a primary moveable sheave sleeve, an intervening member disposed between the axial grooves, an axial tapered groove formed as a part of at least one of the axial grooves which is disposed corresponding to a highest transmission ratio, and an intervening member displacement limiting member arranged to limit an amount of displacement of the intervening member relative to the primary fixed sheave shaft along the fixed side axial groove or the moveable side axial groove.

Abstract: A drive pulley (12) is formed by a piston-cylinder mechanism in which a seal ring (15) is set on an outer periphery of a fixed piston plate (16) that is in sliding contact with a cylinder inner peripheral surface (12d) of a cylinder (12b), and is driven by being supplied with hydraulic pressure. As a control parameter of a surface roughness shape of the cylinder inner peripheral surface (12d) of the drive pulley (12), a kurtosis (Rku) of a von choose curve and a skewness (Rsk) of the roughness curve, each of which is a height direction characteristic average parameter, are used. The cylinder inner peripheral surface (12d) is set to a surface having a surface roughness shape whose measurement values of the kurtosis (Rku) and the skewness (Rsk) are predetermined respective control values or less. With this, it is possible to surely suppress sliding abrasion of the liquid-tight seal member.

Abstract: A belt-drive continuously variable transmission including a lock mechanism for locking a primary moveable sheave of a primary pulley in a highest transmission ratio position. The lock mechanism includes a fixed side axial groove extending on an outer circumferential surface of a primary fixed sheave shaft, a moveable side axial groove extending on an inner circumferential surface of a primary moveable sheave sleeve, an intervening member disposed between the axial grooves, an axial tapered groove formed as a part of at least one of the axial grooves which is disposed corresponding to a highest transmission ratio, and an intervening member displacement limiting member arranged to limit an amount of displacement of the intervening member relative to the primary fixed sheave shaft along the fixed side axial groove or the moveable side axial groove.

Abstract: A method and system are presented for quantifying a data page repetition pattern for a database index in a database management system. In one embodiment, the method includes identifying a database index to provide a basis for collecting a data page repetition statistic, the database index having a database index key. The method may also include collecting the data page repetition statistic based on the database index key, wherein the data page repetition statistic quantifies a data page repetition pattern associated with database queries that reference sequential entries of the database index. The method may further include optimizing a data page access process based on the data page repetition statistic. In a further embodiment, the method may utilize both cluster ratio and data page repetition statistics to evaluate data page I/O and CPU cost.

Abstract: Techniques are provided that determine that a query includes at least one subquery that may be correlated or decorrelated. An internal representation of the query that represents the subquery in both correlated and decorrelated form is generated, wherein the internal representation includes at least one virtual table.

Abstract: A method of, a computer program product for and a computer system for managing statistics in a database management system are provided. A value of a volatility of a statistic is determined. A value of a staleness of the statistic is determined using the value of the volatility. A statistics collection task is generated in response to, at least in part, the value of the staleness exceeding a value of a staleness threshold. The statistics collection task is executed to collect an additional value of the statistic. The additional value of the statistic is stored.

Abstract: Provided are a techniques for processing a query including semi-joins. At execution time, a next semi-join is selected from the semi-joins for execution in a current round of semi-join executions. A reporting threshold is determined that indicates a number of record-identifiers to be retrieved for the determined semi-join. The selected semi-join is executed until the determined number of record identifiers are retrieved.

Abstract: A method and system are presented for quantifying a data page repetition pattern for a database index in a database management system. In one embodiment, the method includes identifying a database index to provide a basis for collecting a data page repetition statistic, the database index having a database index key. The method may also include collecting the data page repetition statistic based on the database index key, wherein the data page repetition statistic quantifies a data page repetition pattern associated with database queries that reference sequential entries of the database index. The method may further include optimizing a data page access process based on the data page repetition statistic. In a further embodiment, the method may utilize both cluster ratio and data page repetition statistics to evaluate data page I/O and CPU cost.

Abstract: Techniques are provided that determine that a query includes at least one subquery that may be correlated or decorrelated. An internal representation of the query that represents the subquery in both correlated and decorrelated form is generated, wherein the internal representation includes at least one virtual table.

Abstract: Techniques are provided that determine that a query includes at least one subquery that may be correlated or decorrelated. An internal representation of the query that represents the subquery in both correlated and decorrelated form is generated, wherein the internal representation includes at least one virtual table.

Abstract: In various embodiments, a method, apparatus, and article of manufacture collect statistics in a database management system. A workload comprising a plurality of database queries is received. Query statistics for the database queries are identified. The query statistics for the database queries are consolidated to provide consolidated statistics. One or more statistics collection requests are generated based on the consolidated statistics.

Abstract: In various embodiments, a method, apparatus, and article of manufacture collect statistics in a database management system. A workload comprising a plurality of database queries is received. Query statistics for the database queries are identified. The query statistics for the database queries are consolidated to provide consolidated statistics. One or more statistics collection requests are generated based on the consolidated statistics.

Abstract: A method, computer program product, and system for processing dynamic statements in a database system are provided. The method, computer program product, and system provide for calculating a first set of characteristics associated with a dynamic statement when the dynamic statement matches one of a plurality of dynamic statements previously processed by the system, comparing the first set of characteristics associated with the dynamic statement to a second set of characteristics associated with one of one or more access paths generated for the one previously processed dynamic statement, and utilizing the one access path to execute the dynamic statement when the comparison of the first set of characteristics to the second set of characteristics satisfies one or more predetermined criteria.

Abstract: Provided are a techniques for processing a query including semi-joins. At execution time, a next semi-join is selected from the semi-joins for execution in a current round of semi-join executions. A reporting threshold is determined that indicates a number of record-identifiers to be retrieved for the determined semi-join. The selected semi-join is executed until the determined number of record identifiers are retrieved.

Abstract: Techniques are provided that determine that a query includes at least one subquery that may be correlated or decorrelated. An internal representation of the query that represents the subquery in both correlated and decorrelated form is generated, wherein the internal representation includes at least one virtual table.

Abstract: Embodiments of the present invention provide a “look-ahead” form prefetch. Look-ahead prefetch may utilize a look-ahead queue to prefetch multiple pages asynchronously. The look-ahead queue may hold a plurality of search keys that are related to a transaction. When accessing a table, an index manager may retrieve the table's index and scan the index based on the search keys from the look-ahead queue to find the RIDs in the table that match the search keys. The index manager may then accumulate these RIDs into a prefetch list. A prefetch manager may read the prefetch list, determine locations for the pages of the table that contain the records identified by the RIDs, and dispatch prefetch tasks to the appropriate storage device for these pages.

Abstract: A method, apparatus, and article of manufacture for optimizing a query in a computer system, wherein the query is performed by the computer system to retrieve data from a database stored on the computer system. The optimization comprises determining an optimal access plan for a first-N-rows query by evaluating a cost of fetching N rows, relative to a total number of rows R in a final results set. Specifically, for a pipelined access plan, this comprises calculating how many rows need to be fetched from each table in the pipelined plan in order to obtain the first N rows from the final results set.