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: Agrobiodiversity Enhancement for the sustainability of the tropical uplands:  An evaluation of agricultural land use  in Liliw, Laguna, Philippines

authors: Wagan, Amparo M.

subjects: Agrobiodiversity Enhancement ABDE

abstract: Agrobiodiversity Enhancement (ABDE) is a strategy that has been advanced for preventing environmental degradation without losing agricultural productivity. However, there is not yet sufficient evidence to support the important role that ABDE might have for managing agricultural land use in the tropical uplands. This research is an attempt to help fill this knowledge gap. The general aim of the thesis was to explore the potential of ABDE as a management alternative for agricultural land use in the uplands in terms of environmental protection, productivity and farmer acceptability. To achieve the aim, a methodological framework for evaluating agricultural land use in the uplands was developed. The methodology aimed at allowing one to understand the influence of agricultural land use on natural resources and farm productivity and the social factors that will most likely influence land users to enhance agrobiodiversity of their production. The methodological framework provided a minimum set of criteria and indicators that can be used for assessing agricultural land uses in the uplands. Main criteria for the evaluation included protection, productivity, viability security and acceptability. The following indicators were included: Shannon Diversity Index, Depth of Topsoil, Soil Organic Matter, Soil Nitrate, Crop Yields, Net Income, Trend in Income and Harvest Loss, Farmer Traits, Farm Characteristics and Farmer perceptions on the influence of farming on the health of natural resources and of the farm workers. The methodological framework also includes a range of methods and techniques for gathering environmental, economic and social data in the uplands and indicates circumstances under which each might best be utilized. 

Using the methodological framework, agricultural land use in an upland area in Liliw, Laguna Philippines was evaluated for protection of natural resources, specifically of the soil quality and for farm productivity and for the social factors that influence the way agricultural lands are managed. Results showed integration of horticultural trees and crops have potential for protecting thickness of the topsoil, reducing nutrient wastage and is more economically profitable than monocropping systems. Specifically, coconut exhibited importance in maintaining thickness of topsoil while lanzones played major role in augmenting farm income and as buffer to income losses from annual crops. Older farmers and women were found associated with agricultural land use with diversified production in the case study area. The Logit model analysis further showed that leadership quality and land ownership are the social factors that will likely influence integration of horticultural trees and crops in the uplands. Other personal characteristics like years of experience in farming, access to other sources of livelihood, land size, awareness of land degradation and effect of agrochemicals on heath of the farm workers have no likely influence on agricultural lands with integration of horticultural trees and crops. SWOT analysis of agricultural land use in the case study site showed that despite the environmental and economic advantages of agricultural lands with diversified production, there are weaknesses and barriers to its further development and implementation. From this assessment, implications for developing and implementing an ABDE intervention program for the tropical uplands were drawn.

text: Agrobiodiversity Enhancement for the sustainability of the tropical uplands:  An evaluation of agricultural land use  in Liliw, Laguna, Philippines Agrobiodiversity Enhancement (ABDE) is a strategy that has been advanced for preventing environmental degradation without losing agricultural productivity. However, there is not yet sufficient evidence to support the important role that ABDE might have for managing agricultural land use in the tropical uplands. This research is an attempt to help fill this knowledge gap. The general aim of the thesis was to explore the potential of ABDE as a management alternative for agricultural land use in the uplands in terms of environmental protection, productivity and farmer acceptability. To achieve the aim, a methodological framework for evaluating agricultural land use in the uplands was developed. The methodology aimed at allowing one to understand the influence of agricultural land use on natural resources and farm productivity and the social factors that will most likely influence land users to enhance agrobiodiversity of their production. The methodological framework provided a minimum set of criteria and indicators that can be used for assessing agricultural land uses in the uplands. Main criteria for the evaluation included protection, productivity, viability security and acceptability. The following indicators were included: Shannon Diversity Index, Depth of Topsoil, Soil Organic Matter, Soil Nitrate, Crop Yields, Net Income, Trend in Income and Harvest Loss, Farmer Traits, Farm Characteristics and Farmer perceptions on the influence of farming on the health of natural resources and of the farm workers. The methodological framework also includes a range of methods and techniques for gathering environmental, economic and social data in the uplands and indicates circumstances under which each might best be utilized. 

Using the methodological framework, agricultural land use in an upland area in Liliw, Laguna Philippines was evaluated for protection of natural resources, specifically of the soil quality and for farm productivity and for the social factors that influence the way agricultural lands are managed. Results showed integration of horticultural trees and crops have potential for protecting thickness of the topsoil, reducing nutrient wastage and is more economically profitable than monocropping systems. Specifically, coconut exhibited importance in maintaining thickness of topsoil while lanzones played major role in augmenting farm income and as buffer to income losses from annual crops. Older farmers and women were found associated with agricultural land use with diversified production in the case study area. The Logit model analysis further showed that leadership quality and land ownership are the social factors that will likely influence integration of horticultural trees and crops in the uplands. Other personal characteristics like years of experience in farming, access to other sources of livelihood, land size, awareness of land degradation and effect of agrochemicals on heath of the farm workers have no likely influence on agricultural lands with integration of horticultural trees and crops. SWOT analysis of agricultural land use in the case study site showed that despite the environmental and economic advantages of agricultural lands with diversified production, there are weaknesses and barriers to its further development and implementation. From this assessment, implications for developing and implementing an ABDE intervention program for the tropical uplands were drawn.

year: 2008

title: Claiming spaces: Maori (indigenous persons) making the invalid valid

authors: Hickey, Huhana

subjects: Maori

abstract: Identity is a shifting paradigm because of the constant movement between identities throughout our lives, depending on the context within which we are identifying ourselves. Once we identify, we place ourselves within a certain construct. When positioning within identity labels, multiplicitous experiences of marginalisation need to be accounted for in clarifying identity frameworks. Barile (2000) asserts that it is the multiple minority status of persons of minority ethnic identity with disabilities that positions them into multiple minority discriminatory experiences with greater limitations and discrimination than those with a single minority status identity. Barile (2000) also asserts that it challenges ethnic minority people with disabilities who work collectively and as a group where they are forced to work as individuals, often in isolation from their ethnic and cultural communities.

text: Claiming spaces: Maori (indigenous persons) making the invalid valid Identity is a shifting paradigm because of the constant movement between identities throughout our lives, depending on the context within which we are identifying ourselves. Once we identify, we place ourselves within a certain construct. When positioning within identity labels, multiplicitous experiences of marginalisation need to be accounted for in clarifying identity frameworks. Barile (2000) asserts that it is the multiple minority status of persons of minority ethnic identity with disabilities that positions them into multiple minority discriminatory experiences with greater limitations and discrimination than those with a single minority status identity. Barile (2000) also asserts that it challenges ethnic minority people with disabilities who work collectively and as a group where they are forced to work as individuals, often in isolation from their ethnic and cultural communities.

year: 2008