title: Is Semantic Query Optimization Worthwhile?

authors: Genet, Bryan Howard

subjects: semantic query optimization

abstract: The term quote semantic query optimization quote (SQO) denotes a methodology whereby queries against databases are optimized using semantic information about the database objects being queried. The result of semantically optimizing a query is another query which is syntactically different to the original, but semantically equivalent and which may be answered more efficiently than the original. SQO is distinctly different from the work performed by the conventional SQL optimizer. The SQL optimizer generates a set of logically equivalent alternative execution paths based ultimately on the rules of relational algebra. However, only a small proportion of the readily available semantic information is utilised by current SQL optimizers. Researchers in SQO agree that SQO can be very effective. However, after some twenty years of research into SQO, there is still no commercial implementation. In this thesis we argue that we need to quantify the conditions for which SQO is worthwhile. We investigate what these conditions are and apply this knowledge to relational database management systems (RDBMS) with static schemas and infrequently updated data. Any semantic query optimizer requires the ability to reason using the semantic information available, in order to draw conclusions which ultimately facilitate the recasting of the original query into a form which can be answered more efficiently. This reasoning engine is currently not part of any commercial RDBMS implementation. We show how a practical semantic query optimizer may be built utilising readily available semantic information, much of it already captured by meta-data typically stored in commercial RDBMS. We develop cost models which predict an upper bound to the amount of optimization one can expect when queries are pre-processed by a semantic optimizer. We present a series of empirical results to confirm the effectiveness or otherwise of various types of SQO and demonstrate the circumstances under which SQO can be effective.

text: Is Semantic Query Optimization Worthwhile? The term quote semantic query optimization quote (SQO) denotes a methodology whereby queries against databases are optimized using semantic information about the database objects being queried. The result of semantically optimizing a query is another query which is syntactically different to the original, but semantically equivalent and which may be answered more efficiently than the original. SQO is distinctly different from the work performed by the conventional SQL optimizer. The SQL optimizer generates a set of logically equivalent alternative execution paths based ultimately on the rules of relational algebra. However, only a small proportion of the readily available semantic information is utilised by current SQL optimizers. Researchers in SQO agree that SQO can be very effective. However, after some twenty years of research into SQO, there is still no commercial implementation. In this thesis we argue that we need to quantify the conditions for which SQO is worthwhile. We investigate what these conditions are and apply this knowledge to relational database management systems (RDBMS) with static schemas and infrequently updated data. Any semantic query optimizer requires the ability to reason using the semantic information available, in order to draw conclusions which ultimately facilitate the recasting of the original query into a form which can be answered more efficiently. This reasoning engine is currently not part of any commercial RDBMS implementation. We show how a practical semantic query optimizer may be built utilising readily available semantic information, much of it already captured by meta-data typically stored in commercial RDBMS. We develop cost models which predict an upper bound to the amount of optimization one can expect when queries are pre-processed by a semantic optimizer. We present a series of empirical results to confirm the effectiveness or otherwise of various types of SQO and demonstrate the circumstances under which SQO can be effective.

year: 2007

title: Modified Output in Response to Clarification Requests and Second Language

authors: Ogino, Masayoshi

subjects: second language acquisition

abstract: Modified output, second language (L2) learners' reformulation of their own utterances, has been attracting researchers' interest as an important component of learner interactions, and as a manifestation of interlanguage development and psycholinguistic processing. 

The output hypothesis (Swain, 1985, 1993, 1995, 2005) claims that the act of production constitutes part of the process of L2 learning in terms of noticing, hypothesis testing and metalinguistic functions.  This hypothesis has been used as a theoretical framework to investigate the relationship between modified output and L2 learning (e.g., McDonough, 2001, 2005; Nobuyoshi  Ellis, 1993; O'Relly, Flatiz,  Kromrey, 2001; Takashima  Ellis, 1999).  However, the empirical evidence from these studies does not yet appear to confirm unequivocally that the production of modified output facilitates L2 learning. 

The present study further explored the impact of modified output on L2 learning, by means of an experimental pre-test, post-test and delayed-post design.  The production of modified output was triggered by one type of implicit feedback, clarification requests.  The data were collected from 28 undergraduate students who were learning Japanese as a foreign language.  The target linguistic feature was the negation of adjectives in Japanese, and a total of 1,011 negations were elicited and analysed.  The impact of modified output on L2 learning was measured in two different aspects of potential outcomes of modified output (i.e., grammatical accuracy and interlanguage development).  In addition, the study investigated whether the non-targetlike forms which participants previously modified were then produced in the subsequent situations of use.  

The output hypothesis was originally framed in terms of the relationship between output and grammatical accuracy, but the findings of the current study suggest that production of modified output in response to clarification requests may facilitate the progress of interlanguage development towards targetlike use even when its immediate impact on grammatical accuracy may not be observed.  Therefore, the present study lends at least partial support to the claim of the output hypothesis.

The results did not clearly demonstrate whether or not production of modified output might sensitise learners to avoid the use of the same non-targetlike form that they have previously modified.  This indicates a possibility of the limited role of production of modified output in L2 learning, and suggests that the follow-up feedback to learners' modified output may be necessary to maximise the impact of modified output in facilitating L2 learning.

text: Modified Output in Response to Clarification Requests and Second Language Modified output, second language (L2) learners' reformulation of their own utterances, has been attracting researchers' interest as an important component of learner interactions, and as a manifestation of interlanguage development and psycholinguistic processing. 

The output hypothesis (Swain, 1985, 1993, 1995, 2005) claims that the act of production constitutes part of the process of L2 learning in terms of noticing, hypothesis testing and metalinguistic functions.  This hypothesis has been used as a theoretical framework to investigate the relationship between modified output and L2 learning (e.g., McDonough, 2001, 2005; Nobuyoshi  Ellis, 1993; O'Relly, Flatiz,  Kromrey, 2001; Takashima  Ellis, 1999).  However, the empirical evidence from these studies does not yet appear to confirm unequivocally that the production of modified output facilitates L2 learning. 

The present study further explored the impact of modified output on L2 learning, by means of an experimental pre-test, post-test and delayed-post design.  The production of modified output was triggered by one type of implicit feedback, clarification requests.  The data were collected from 28 undergraduate students who were learning Japanese as a foreign language.  The target linguistic feature was the negation of adjectives in Japanese, and a total of 1,011 negations were elicited and analysed.  The impact of modified output on L2 learning was measured in two different aspects of potential outcomes of modified output (i.e., grammatical accuracy and interlanguage development).  In addition, the study investigated whether the non-targetlike forms which participants previously modified were then produced in the subsequent situations of use.  

The output hypothesis was originally framed in terms of the relationship between output and grammatical accuracy, but the findings of the current study suggest that production of modified output in response to clarification requests may facilitate the progress of interlanguage development towards targetlike use even when its immediate impact on grammatical accuracy may not be observed.  Therefore, the present study lends at least partial support to the claim of the output hypothesis.

The results did not clearly demonstrate whether or not production of modified output might sensitise learners to avoid the use of the same non-targetlike form that they have previously modified.  This indicates a possibility of the limited role of production of modified output in L2 learning, and suggests that the follow-up feedback to learners' modified output may be necessary to maximise the impact of modified output in facilitating L2 learning.

year: 2008

title: Tangi and State Funeral: Te Arikinui Dame Te Atairangikaahu and Prime Minister Norman Kirk

authors: McRae, Karyn Okeroa

subjects: Tangi

abstract: The tangi of Te Arikinui Dame Te Atairangikaahu (Te Arikinui) in 2006 paralleled the State funerals for New Zealand Prime Ministers like Norman Kirk who died in 1974. State funerals require the huge mobilization of people and resources and always attract the attention of the national and international media. The death of a Prime Minister is news worthy, but what of a minority indigenous fourth world leader like Te Arikinui? Why did her passing attract so much media attention? In this study I argue that media representation of the tangi of Te Arikinui was largely about social, cultural and symbolic capital. In media saturated societies such as Aotearoa/New Zealand, through mainstream media outlets like TV One News and the Waikato Times, Te Arikinui’s tangi event claimed a dominant space in the lives of Maori and non Maori alike. The data source includes print news media coverage of the tangi of Te Arikinui and the State funeral of Norman Kirk. Descriptive narrative and abductive analysis inform the methodology used in this study. As expected, print media reporting of both events progressed through the three stages identified by Durkheim, those of, separation, liminality and reincorporation. The ownership of death, the deceased and the continued possession of their mortal remains, itself a cultural object with symbolic and cultural capital, reflected the actual power and control of the possessor. State funerals and tangi are about the ritualized performance of grief and mourning, and require the appropriate social, cultural and symbolic capital for its enactment.

text: Tangi and State Funeral: Te Arikinui Dame Te Atairangikaahu and Prime Minister Norman Kirk The tangi of Te Arikinui Dame Te Atairangikaahu (Te Arikinui) in 2006 paralleled the State funerals for New Zealand Prime Ministers like Norman Kirk who died in 1974. State funerals require the huge mobilization of people and resources and always attract the attention of the national and international media. The death of a Prime Minister is news worthy, but what of a minority indigenous fourth world leader like Te Arikinui? Why did her passing attract so much media attention? In this study I argue that media representation of the tangi of Te Arikinui was largely about social, cultural and symbolic capital. In media saturated societies such as Aotearoa/New Zealand, through mainstream media outlets like TV One News and the Waikato Times, Te Arikinui’s tangi event claimed a dominant space in the lives of Maori and non Maori alike. The data source includes print news media coverage of the tangi of Te Arikinui and the State funeral of Norman Kirk. Descriptive narrative and abductive analysis inform the methodology used in this study. As expected, print media reporting of both events progressed through the three stages identified by Durkheim, those of, separation, liminality and reincorporation. The ownership of death, the deceased and the continued possession of their mortal remains, itself a cultural object with symbolic and cultural capital, reflected the actual power and control of the possessor. State funerals and tangi are about the ritualized performance of grief and mourning, and require the appropriate social, cultural and symbolic capital for its enactment.

year: 2010