What are the algorithms for biometric identification in large database?
I think that a very nice example of what you are talking about saying the word bigger, is probably a microarray transciptional analysis of RNA extracted from a biological sample. Simplifying, in these analyis, each observation is analised on, up to 10000 genes expression levels of different mRNA coding genes. Thus, from these type of molecular biology experiments, we obtain matrices with few observations (d, the samples) respect to the dimensions observed (k, the target gene expression levels). Well, d &lt;&lt; k. In this situation, in order to perform a classification-like task, and to reduce the problem of the overfitting related with dimensionality maledition, the ways that we might follow are several: 

1) PCA: it is a good tool to visualize multidimensional datasets reducing dimensionality and noise level in the consolidated and standardized data. Problem: it is an unsupervised machine learning algorithm. Alone, it haven't the capacity of class discrimination. 

2) PCA-LDA is a good combination, where PCA eliminates  hyperdimensionality and background in our data sheets, and than LDA (linear discriminant analysis) finds the directions onto the new subspace of characteristics, that are able to maximize variances between classes and decrease the variances within these. For this reason LDA is known as a kind of supervised machine learning technique. Furthermore, PCA and LDA are usually used together because LDA applied on high dimensional datasets could lead us toward overfitting problems. After the training of PCA-LDA pipeline, being LDA a classificator object trained and shaped on the principal component subspace, you can use this to examine new unknown samples or observation and predict its class by similarity. e.g. recently, Martin et al., on a Nature article talk about PCA-LDA approach to identify and than to predict cancer cells from those are normal, starting from ranman spectra of tissues.

3) PCA-LDA on transpose matrix: to use as better as possible the huge dimensionality, some authors used to transpose the initial matrix in order to force positioning of genes as rows and samples as columns. Then, the subsequent LDA is performed not on PC scores, but on loading factors of the eigenfactor matrix obtaining thus the list of the most important discriminant gene expression levels to segregate normal samples to cancer ones.